I haven't read the entire thread, but one crazy idea where we don't sell, and now that Laporte is not happening, could be to convert him back to becoming a defender. He won't have to run around as much as he once did/rely on pace if he can position himself well enough (although that didn't seem to work enough for MDM this season), and would provide us with an incredibly skilled passer, who won't give the ball away, as well as can use his world class vision to be our own version of Bonucci, arguably even better.
His lack of work rate or perhaps interest in defending when as a midfielder anymore would cause concern, as would how little he heads the ball for someone of his size. Besides a million other reasons this would make some go mental, it would be quite interesting to see.