He won't sign a new deal at somewhere he doesn't want to be though. Why give the club any leverage when he doesn't want to be there, if they do indeed refuse a move?
If he throws his toys out of the pram, his people trail is through the media, and down tools, his value will indeed go one way, not the one you hope.
The kid backs himself, he's been one of the best players in the Bundesliga, in his first season, he's clearly ready to play for a big club.
I obviously hope he doesn't want the move, and Bayern's interest is over stated. But I'm a rational person, and the sad reality of modern day football is that players have the power. This is said over and over by ex-pros who are now pundits, they're much more privvy to how things work, so I'm inclined to believe it. And there aren't many examples of players being defined moves by big clubs kick on, stay out for a long time. Sure, it happens, but it's the exception, not the rule. If he wants to go, Bayern offer big money, it's likely he goes there.