"We have recently completed a transaction with Comcast to simplify our relationship. Disney has acquired all the Marvel and Star Wars rights held by the combined Comcast-FOX entity. This includes the Marvel theme park rights held by Comcast, which will revert to Disney within a four year time span. In exchange, we will forgo the buyout fee due to Disney from the proposed 21st Century Fox acquisition and transfer the theme park rights to the Avatar franchise to Comcast within the same four year time span. We won't get into the specifics of this two way transaction, but we expect it will drive attractive returns for Disney."
If Comcast buys Fox, they will have several things that Disney wants:
A share of Sky
A share of Hulu
Avatar
Star Wars Episode 4 distribution rights
X-Men rights
FF rights
Theme Park rights
Hulk and Namor rights
Rights to thousands of other films and TV shows
etc. etc. etc. etc.
Comcast would be deep in dept and Disney would be flush with cash.
Disney would likely try to purchase some of those assets and Comcast would likely be interested in getting some cash by selling the ones that aren't key to their long-term plan.
How much Disney would get and how much they would pay for what they get would be a negotiation and depend on the specifics, but after Disney bid $71 billion for Fox, they're not going to walk away without trying to get something else, and after Comcast paid $90+ billion for Fox, they're going to entertain offers.
X-Men rights and FF rights are worth more to Disney than they are to Comcast, so those will be some of the easiest items to come to an agreement on.
Disney isn't going to pay exactly $1.52 billion and get exactly the FF rights and the X-Men rights. That's a ridiculous oversimplification, but the $1.52 billion is part of the cash disparity that would exist between Disney and Comcast if such a hypothetical happened, so Disney could use that cash plus other cash to get items they want.