What it comes down to is 21st Century Fox the Corporation has decided to concentrate on it's news, sports,and TV networks and get out of the content producing business (except. of course, for News and Sports;depnding on outside providers for it "fictional"programing). Fox is selling,and only question is who will give Fox the Best Deal. I think that Fox was not quite happy with Disney's initial offer,deided to shop Fox studios around,and decided that Disney would probably give them the best deal after all.
The bit about sports is intriguing in that article, maybe part of the deal would be ESPN going over to Fox, since ESPN has become a major headache for The Mouse.