This has been discussed in the past and I don't think we have every come to a consensus on whether they could do a Marvel themed hotel. The interesting question is, if they are allowed to do M&G's outside the parks with the restricted characters, why haven't they done it yet?
Hard to monetize maybe? Not many M&Gs occur outside of the parks anyway. I guess you could do one at the springs... Can't really see them doing a character breakfast, at least not yet.
My bet is that they could do Marvel M&Gs on property, but why do it? Makes little sense to incur the wrath of Universal and almost certain expensive litigation for something that involves expensive face characters but provides no tangible ROI.