From a more cynical perspective: Who's going to have to actually change the oaths? The politicians. The same politicians who want to be able to sell the wars as protecting the motherland. That change seems to be unlikely to be implemented, because it takes power away from those who want it.
No, it wouldn't have; they just would have changed it back, as they violated lots of other terms imposed on them to prevent them from being a threat.
And if the Allies hadn't been just as eager to dump the restrictions, it would have interfered with the Allied response to Nazi Germany.
Controlling war isn't a matter of thinking up rules that will prevent it as long as no one breaks them. If it were, the Kellogg-Briand Pact in 1928 would have solved the problem.