Hey hopefully it's not too late to do this I just saw a video about this and wanted to come here too, first of all, welcome @EA_Shepard and I wish you the best of luck.
I have been a fan of PvZ for some time, mainly the shooters as It was the first PvZ game I ever played, I have been playing pretty much since GW1 first came out. I love this game and would love to see it grow, I understand that from a company's point of view, the shooters did not deliver as expected especially Battle for Neighborville. I am not here to blame or complain but I am sure we can all agree that there were some not good decisions made with this game, I like the game and love to play it but I always felt like removing the variants was the main reason why the game didn't do well (ofc there were many other reasons but this just felt like it was the biggest one), I remember seen back in the day how a lot of people complained about the variants being removed and all that. My point is that GW2 always had the potential to be one of the biggest and it should come without saying that people really like the variants, there are mod communities that make their own variants and it just feels so refreshing to play. I am trying to say that GW2 could easily be revived into a game that matches big names, especially nowadays when titles like Call of Duty, battlefield, battlefront, and many others have flopped and become mediocre games. I am not saying make GW3 I am just saying that just simply adding new content can revive the game and make people want to come back. it could be just adding 2 new variants or a new character every couple of months and maybe a new map here and there, that would just be enough to get the game back up on its feet. Of course, I understand that EA is a company and money is the final goal.
By adding new variants you could easily make the typical move of the first 2 weeks of the new variants coming out there is a pack you could buy that gives you the variant straight up but you can only buy it with real money or else free to play players can just grind it out like any other character in the game (of course the more characters and variants the more money can be obtained this way).
EA can also implement crossover variants that can only be obtained with real money, like how GW1 had the Cheetos variants and the blue peeshoter that was all bout fruits or something like that.
There could also be a second Rux but call him something like Xur and it is Rux's twin brother who is way cooler, Xur's thing is that he sells things that you can only buy with real money like he could sell legendary hats at "discounted" prices, but Xur is a very high-class gnome and he only sells the best of the best but he doesn't just spawn these items he has to go find them, this means that Xur has periodic shops, meaning that he comes with items once every month and a half or something like that, this would be so Rux who is there all the time doesn't get overshadowed by Xur, while Rux sells 5 items Xur only sells 3 items. I was also thinking that on top of this, the game can take inspiration from some of the character abilities that are in BFN and you can unlock these abilities by doing challenges for the characters they are meant for, these challenges take some time and are not that easy to get so that if you put them on Xur's shop a lot of players might just decide to buy the ability with real money rather than do the challenges. Xur could also sell variant parts for example that one part that you are missing so you can just finish the set and get the variant. Making Xur be smart and targeting the player's preferences, if the player is been playing a lot of Cactus then there is a big chance that Xur will be selling something Cactus-related in his shop.
I wouldn't suggest making a battle pass as this could result in the team focusing only on the battle pass and then everything else gets boring and then the game dies again. but if you must DO NOT make it a paid battle pass, this is because the game is already pretty free to play and now just out of nowhere starting to lock things behind a paywall is not what the game is, on the other hand making it a pretty grindy free battle pass could lead to a lot of players just paying to instantly finish the battle pass and well that's good because money. you could make it so that when a new character is realized into the game, you can unlock it on the battle pass and have it released with a variant so that the variant is the last thing you unluck on the battle pass, and when the battle pass is over, all this cosmetics and the character and variant go into the card packs and now you can get them there making space for the next battle pass.
Now there are also many ways to keep the community engaged apart from new characters. Make communal events by making the player base separate into 2 teams either you are with the zombies or the plants, now this month's challenge is seeing which team gets more kills in online matches (if you play plants or zombies in the match it doesn’t make a difference, what matters is the team that you pick on the lobby of the game where all the kills you get in the match will go to) and the winner gets a cosmetic that can only be obtained by winning the challenge it could be like a golden cosmetic or a emote with a cool victory aura effect or something like that and if you are on the losers side there is a chance you can buy it on Xur's shop but its a less cool version of the actual item, like this one is only silver color and or the victory aura for the emote is less flashy or a different color.
There could also be something like a Boss battle event, where there is a boss that is pretty hard to kill and either you play only plants or only zombies, or who knows maybe the boss is a massive gnome or a massive shark or something that makes plants and zombies work together to destroy and yeah there should be something that the players win after beating the boss or maybe if you can beat the boss at a certain speed you win a cosmetic like for example if the boss is the massive shark if you beat it in less than 10 minutes you win a shark helmet that has a bubble effect or something that incentivizes players into playing and make it so many players can join and fight the boss, maybe the boss has a new character trapped and you can only unlock the ability to use the character by beating the boss, (but of course you still need to get the character first, people can still play the event even if they don't own the character).
New maps, like a funny map where the characters are the size of ants and they are fighting on top of Dave's table, and there are massive tacos everywhere and soda cans, a TV remote, spoons and forks, and all that. or a map in an abandoned mineshaft made by the zombies where they were trying to find new materials to make their weapons with. If it really comes down to it this could be DLC maps that can be bought with money but maybe make it so it is a bundle of maps and maybe you also unlock the new character or something like that or crossover DLC in which you unlock a new map to play on and the new variants or characters.
New game modes, like making a game mode where each team has a king, the goal is to kill the enemy king first. But maybe to make it more interesting each team has a certain amount of lives and they can only replenish these lives by getting their king to kill players too, each kill that the king gets turns into one life for his team, and the king has 100% more health and they regen slower and get 50% less healing from any sources, the king of each team is chosen randomly and if the king is getting healed by 3 or more sources, the healing becomes damage as we do not want teams that are all just scientists and sunflowers, and maybe it makes it so that if the king is staying too long in the same place a massive cannonball will hit that place and deal a lot of damage to anything there.
Lastly, I want to touch on new characters and variants again, as for some time you can just take the chargers from BFN and put them in GW2, with some minor changes and they are ready to play, and you can add variants to them like I would love to see a Toxic NightCap that shoots 3 Poisson stars every click, it does less damage than normal NightCap but every third hit on the same target will activate Poisson damage. Or a special Action Hero that shoots 1 arrow but his attacks don’t do too much damage even the charged attack, but every third attack on the same target will activate all the arrows to explode and it will deal % max health, like maybe 7.5% or something like that.
But yeah these are all just crazy ideas I always had and I know it's a lot to ask for but GW2 truly has the potential to be good again. And this is not only for this game a lot of ideas can also work for Titalfall 2 and also make that amazing game come alive again. Thank you for reading and have a lovely day everyone.