I'm not saying it's not a risk, I just don't think it's as high a risk to guide the decision making here. If he values having a couple of Bundesliga medals that much then fair enough but I don't think that's anywhere near worth the sacrifice he'd be making.Collecting a check on the beginning of a long term contract, not the last year of his deal. Kane dropping off due to injury or some other factor is not some improbable scenario. It happens more than you think
It wouldn't actually have to be a shot at only one or the other though in fairness... He can push on towards the former (even at Spurs next season) and have his pick of club next summer that can offer a serious shot at the latter as well (Chelsea, United, Liverpool etc.), all the while pocketing a ridiculous sign on fee. The only things that will prevent it being a 1) dramatic drop off in form - which could happen at Bayern as well or 2) a freak career ending injury - which could happen at Bayern as well.PL all-time scorer is a record that can be broken, trophies and honors like the Ballon d’Or are permanent.
Ok on 2) he would then be able to collect his contract from the treatment table but I personally wouldn't have that high up in my considerations if I was him e.g. already loaded and with a greater probability of a better financial package from the future sign on anyway. Very very very risk averse for the only guarantee of a few Bundesliga medals.