I don't think Cross-Play should happen in some ways people are talking about here.
- Console players should not play against PC players due to control differences that might give PC players the upper hand, especially in PvP.
Unless those PC players are using controllers, then the game would disable keyboard and mouse input altogether. (Console players should have the option not to be match made against PC players at all and that should be the default option.) <- I'm not sure about allowing PC players at all, no offense.. that is all because of hacking and using cheating software... Not accusing anyone here, but this is bound to happen at a point. And I'm not sure if PopCap can handle anti-cheating properly or have the staff to monitor all that like other games. - In lobbies, console players may cross-play with each other. PS4 and Xbox One as teammates or enemies.
- If a console player wants to play with a PC friend or the opposite way around, they will join a PC lobby with them regardless of the mode.
- Add an option for PvE (for OPs and future PvE Events) to be match made with PC players in the options. The same thing should be added to PC players "Allow console players for cross-play". If both of they have it checked, then they can play with each other.
- Add an option for console players only that allows them to play against PC players in PvP modes if they ever wished to do that. By checking that option players should be notified that they will be match made against keyboard/mouse players and that they can report players for any foul behavior.
- Players should have the ability to report others. (I'm sure that would be one of PlayStation's requirements because when a kid gets out of the PS platform with Cross-Play, they won't be able to report others for harassment/toxicity unless they were on PlayStation.)
- Players should have the freedom to switch between platforms while having their progress carried on as @ippig mentioned.
With all that said, as one of the developers said in the last stream, it's a huge system that requires a lot of thoughts and considerations to implement well. The primary focus right now is bug-fixing and making sure this game is working on all platforms with no issues. And then comes the balance/Quality-of-Life changes.
And yes, this game needs Cross-Play because it's not free to play... And the number of players is significantly lower than, let's say, Fortnite...
Cheers,*1
* This is my own personal opinion to make it fair and square to all players. Not all players might agree with PC <-> Console PvP matchmaking. This happens in many gaming communities.
* Sorry if some of what I posted was mentioned elsewhere. But I just wanted to make it in clear points.
*1 PvZ 1's original composer's last music before she left PopCap. Unrelated to the topic, but I was listening to it while typing this.