Why do people think Chelsea are in for him? They've just signed Pulisic on big money and Hudson-Odoi on a fat contract too, as well as having Willian as a regular starter, Mount at no.10 etc. Sure he could make a big contribution for them but he's hardly what they're crying out for. A quality LB, a leader at the back and a top striker would appear to be much more important for them from my point of view.
Secondly, why do people think Chelsea are more of a draw than United right now? They're not exactly playing amazing football, less fans, less money, less history, and about the same likelihood of doing anything in Europe. I'm really not convinced.
Dortmund or United are the only obvious clubs for him right now in my view unless Madrid fancy him. Juventus could be appealing of course but I doubt they're interested.