At around 4:47 I think Seth “leaked” (and I use this word lightly) an unknown stage with marvel cameo appearances. Days of Futures past if I heard correctly and possibly new characters playable at evo (towards the end of the video).
Around 4:50 Seth mentions a “Days of Futures Past” stage which was an X-Men story line in which Senator Kelly is assassinated and the sentinels took over forcing the mutants in into internment camps. This is an alternate future kinda thing but apparently it was a really popular story arc. He also mentions possible cameos of characters who didn’t make it in showing up in the stage.
As far as the “official” character reveals go, he mentions there might be more playable characters at evo which I would assume means that the reveal trailers would be coming soon possible during comic con kinda like what they did with Thor and Ammy at last years comic con where they waited till the panel to “reveal” them. Funny how at both events both sets of characters got leaked lol poor Capcom.
Sorry if old
Edit: When talking about the cameos he more or less is referring to mvc2 vets (need to watch again to be sure)