Just cut to the end now. He comes back from banishment.
Or does he? Maybe just after he is being welcomed back and about to regain his respectability...some long forgotten worshipper of Daenerys, or her ghost, or a dragon, or a ghost of a dragon, or maybe a new lover who turns out was a worshipper of Daenerys...stabs him in the heart (or back) in the last minute.
You know, just to piss off the last remaining fan or 2 of the franchise.