Microsoft would not replace Satya Nadella with Bill Gates at this point. One of the counter points is very clear: they forced Bill to relinquish his chairman role. The board now would never allow Bill to return as CEO unless the company was in extreme crisis and they needed a temporary leader; they successfully just pried Bill's hands off of a big point of control over Microsoft.
There's also no evidence Bill is a stronger candidate to manage the current conglomerate version of Microsoft than Satya (who appears to be doing a fine job so far). Based on the work Bill did the last several years he was actively involved, he has lost a step or three. Further, Bill's age at this point - 60 - is a serious problem, Satya can run Microsoft for 12 years before catching up to that. Jobs by comparison returned to Apple at a mere 42 years old.