Catching up with the posts from last night and I don't think this is exactly true. Yeah, someone who's never played a video game in their life might be confused, but most folks with even moderate video game knowledge have heard of Devil May Cry, Ace Attorney, Dead Rising, Okami and maybe a handful of others. A lot of people remember Viewtiful Joe as one of the premiere GameCube games and Ghosts 'n Goblins is one of the faces of "NES Hard" as well as being popular enough to make the NES Classic lineup. It's my opinion that Capcom has the best line-up of IPs of any video game company outside of Nintendo. Again, that's not to say Final Fight or Strider are as well known as the Avengers movies, but yeah. Marvel vs. Capcom wouldn't have ever happened if both companies weren't popular and successful in the first place.
And as far as general Marvel fans go I'd still think a lot of them would be excited to see a current-gen fighting game where Cap and Iron Man can square off, the other half of the roster would just be a bonus.