I think the biggest question that has to be answer revolves around the deals that are already in place with entities such as Universal Studios. For all we know, Universal Studios has rights to all characters for the next 10-20 years. In that case, to the fan of the Disney parks, we wouldn't see any changes for years.
The comic book area of Universal is themed very well. Actually, the buildings are themed well, as you truly feel like you are walking in a comic book...though I wouldn't say any of the rides aside from Spider Man (which is better than anything at Disney, in my opinion) are themed very well.
It will be interesting to see the following:
1) How long does Universal have the rights to call that part of their park "Marvel Super Hero Island"?
2) How long do they have the rights to the actual rides that are already there? I would think that this would extend beyond their contract for the name, as it is easier to rename the section of the park than it is to retheme all of the rides.
3) Does Universal's contract extend to everything that Marvel had previously made (Iron Man), or just what they had already created rides for? That is a big one for me. If the contract is limited to what is already in place, then I would assume that Disney could create a comic book themed ride as soon as possible. That would be cool.
4) If Disney decides to pursue rides/attractions, will they make them part of an existing park or create a new one. I think Marvel offers enough to support an entirely new gate, but I could see it as an addition to Hollywood Studios (more likely). As a new gate, perhaps it could be a new park dedicated to "thrill" rides, which Universal has outdone them with. As my sons are getting older, I would love to see a park filled with thrill rides.