Nor with the fact that OP is approaching retirement age... if you figure 10 years from beginning a PhD program to tenure (which certainly isn't a hard limit, bu

Nor with the fact that OP is approaching retirement age... if you figure 10 years from beginning a PhD program to tenure (which certainly isn't a hard limit, but probably isn't an unreasonable basis to start from) then they might have only 10-15 working years left after 'getting there'. While hiring and tenure considerations would word it _very_ carefully to avoid the appearance of age discrimination, I suspect that would factor into any such decisions.