I'm aware of that rumor. But I didn't take into consideration here for many reasons. For one, it's still just a vague rumor and we have to wait for the official confirmation on it (It could have easily been made up by someone speculating that Marvel would leave out all the X-Men due to CompleX related issues).
And two, it's something we heard only recently. The rumor started to circulate only after Marvel had already revealed ResurreXion and talked about X-Men getting a rebirth.
And third and most important, if the game does exist and will in fact be released next year then that means that it's already under development and that the licensing deals for it have been signed most likely. So even if MvC4 doesn't have the X-Men in it doesn't 100% confirm that the thawing between Fox and Marvel hasn't been an actual thing. After all, we did suddenly get more x-merch out after the talks about Fox and Marvel having negotiated about the shows they are partnering on and Marvel has promoted Legion. So some kinds of deals must have been made. But it might only affect the licensing deals Marvel was making during the negotiations with Fox and licensing deals they make from now on. So for all we know the original licensing deals between Marvel and Capcom might have been made during the time when Marvel was keeping X-Men licenses out of every deal they made.
Best ways to tell if the thawing of Marvel-Fox Cold War is real is by observing the Marvel merch and games that are released in the future and being negotiated as we speak. If there are more X-Men among them then there has been an improvement in the relationship and if not, well... then the things continue the same. And personally I've been a bit sceptical about these deals between Marvel and Fox having much of an effect on things in the larger scale from the start. But we'll see I guess.
I'm sure that some fans would have complained that bringing back the actual gold and blue teams from the 90's would also be just a rehash of old lineups and same goes for having another book about NXM kids BUT at least those lineups and characters have been gone for at least a decade and in some cases even longer so it would have been more of a different thing and a bigger change than the ones revealed. These are literally just re-packaging of what we have had for the past 3-4 years. And at least the 90's teams and NXM seem to be fan favorites while JGS/Bendis kids and teen O5 seem to be disliked by a sizable portion of the fan base because Marvel just keeps giving us them and not much else.