It's not the end of the game. It's not the sunset of the game.
What it is, is a moment where some players are coming to an uncomfortable truth: This game isn't made for them. They're not the target demographic and they're aging out of the game. But that's okay! The game will continue without you and new players will sign up. You'll be replaced and you'll be forgotten and that's okay because it's just a video game and there are thousands of them out there. You can put this one down, never log into it again, and then pick up Dragon Champions or Strike Force or just refresh Facebook until an ad for a new game pops up and play that. Then you can have a ton of fun in the early stretch as you figure things out and work on your roster. And then you can get bored and frustrated again in the middle stretch when you hit the max level and run out of fungible content. And then you can join a competitive guild and feel that stress again. And then you can go to the forum and complain that there isn't enough to do. And then you can move onto another game.
It's okay. All of this has happened before and all of this will happen again. You'll keep on repeating the same patterns until you reflect on why you play these games. Hopefully once you know that answer you can start enjoying them again.