I would argue that the chances of him next season wearing a UTD, Chelsea (or, even, dare I say it.......an Arsenal one) shirt are a hell of a lot higher if he goes to Bayern.
If he goes there and Chelsea offer £100m next season they'd take it and he could sign without the risk to his reputation or his relationship with Spurs fans.
If people are worried about him turning out for another London club then going abroad for a year is probably the only way he can do it without a massive backlash
Once he leaves Spurs I could not care less who he plays for. Bit of a small club mentality!