Spider-man is Sony exclusive, because Sony have the rights to the character - the movie rights for a looong time, and the video game rights since 2014, when Activision lost them. The Iron Man VR thing isn’t really indicative of anything, because a) Microsoft don’t have a VR headset competitor, and b) SIE is publishing the game. There’s no indication that Sony have any sort of exclusivity to the Iron Man character or anything.
But perhaps most importantly, if this game was exclusive, we probably would have heard about it when it was announced, because Sony would want to crow about it.
If this is the beginning of a slate of new Marvel games, as media coverage has indicated, I’m hard pressed to believe that Marvel/Disney would want them all exclusive to a single platform.
I’d say there’s a 90% chance this is multiplatform, and the only real question is whether Eidos Montreal managed to make a business deal with Sony to get Spidey in the game.
Anyway, I’m interested to see the game. Most of all, I’d like to know what genre it is.