The Injustice 2 guesses topic looks fine to me, although maybe having turning it into "guess the roster" could work well. Since we'll likely have weekly announcements for the game from now on (even though I said it might not be enough time before release, I think it's still possible), it'll be way easier to keep that topic alive.
Not really sure about MvC Infinite though. We don't even know the release date for that game, there's no way to know when Capcom might show something and when they won't.