But I'll be so fucking old by then that a move may not make sense.

Maybe so. But the other thing to consider is, five years after the decision not to go, will you regret that decision. Might be better to go and possibly not fully succeed, at least you'll have given it a red hot go and have no regrets. And with that in mind, you can plan your move such that you can extricate yourself if necessary while minimising the cost of it.