Rocket League
Titanfall 2
Tekken 7
Gwent
Pure Chess
The Titanfall 2 devs have commented on crossplay?? That is by far the game that needs it the most with its small population.
There is one
ACTUALLY valid concern and problem about this cross play precedent Minecraft is setting though; How long before games start making so that to invite, join and party up with friends you can
ONLY use their ingame 3rd party friends lists and not the console OS?
Gone the days where I can just look at my friends list, open a friends profile and invite or join them in a game. As long as having the account for cross play friends lists and all that is optional I'm okay with this, but I don't want it if its going to ruin the current experience. Look at Warthunder on PS4, in order to play with friends you have to make an account in the game, search for your friends by their Warthunder name, and then join and invite them that way. AFAIK you can't use the PS4 OS to do this, but it does enable cross play and parties with the PC version. Personally as long as it is optional and people can still play games with their friends like they had before I see nothing bad about this.
That's the only real problem I can think of with cross play, this doesn't apply to games just having cross-play matchmaking which there is no downside to besides mouse and controller differences, but that's not consoles.