"semi mugen"? No. Semi "Marvel vs. Capcom 2", YES !! (I would think that the "hyper" sequence with a picture of a Ryu in a triangle moving in the back would have been a dead giveaway of that)
The reason why you see CA, and Spider/Iron/Ice Man is just to show the people that there are no limits to how many (Capcom) characters can be added. I personally would love to see all of the X-Men characters ever created in here
This will start as XvsSF game, but, who knows where it will end up. Still, don