Cano significantly loses value if he moves from 2B to 1B. A significant portion of his value is tied to his position. As a 1B he'd be very good, but not elite or best in the game, therefore not a candidate to make elite position player money.
Also, no, Cano is not the "one player you can bet on for the next 8 years". He's in his 30's, and you'd need for him to stay in a MIF position and play it at least competently for his contract to make sense.
Also, so you're saying that because the Sox made a s***** signing once and lived through it they should continue to do so? That's awful logic. I'd like to see them stick it to the Yankees to, but not by handcuffing themselves to a dumb contract like the A-Rod one. That doesn't make any sense.