People are freaking out too much here. The big clubs in England might have some help being out of major European competitions, but they will always be a disappointment there with the English expectations. So far we have 5 title contenders, excluding the current champion and Liverpool, but only 4 CL places...
Say United signed him for 20m NET salary and they couldn't make CL next year (>20% chance). Is it Mourinho building and the board backing again? Even if that is the case for a full 2nd season, it won't be for the 3rd! The same goes for the rest of those teams...
If Raiola is smart he will just make Elkann open his wallet and back his words. He has money to spare and plays the big shot.