Is my dog too dangerous to be re-homed?

Yeah i have a rotti and 2 dobermans.. the rotti and 1 of the dobermans are really protective of us and the home, they dont like other people or vehicles. I would never re home my rotti since he is the worse, plus he would never leave anyways. If i was in your position and my rotti had to go.. i would probably put him down.. he is getting old anyways.. and he lived a good life. Its just to much on your shoulders to wonder if the dogs going to actually really hurt somebody or not. Its sad but that's what has to be done. hope i helped a little.