Indeed. Also, what truly expansive franchises does Marvel have worthy of the Square Enix treatment? Excluding Spider-Man, who's Sony-exclusive, and Avengers solo adventures (as I assume the Avengers project will scratch that itch), you could perhaps have a cosmic/Guardians-focused title, but that still leaves 2 of the announced 4 collaborations unaccounted for. I could perhaps imagine a substitute for Marvel Heroes Omega, since that game seems to be going the way of the dodo, although I guess the Avengers game could cover a lot of that stuff as well.
So, unless by the time we get there Marvel has created a strong new cinematic franchise, which is entirely possible, I do see a Square Enix-made X-Men game being one of the four announced titles.