I imagine that Obama will not veto a resolution admitting the newly created Palestine (by UNGA) to the UN. Sanctions on Israel may be vetoed, but they are not the only means of causing trouble. With a recognized Palestine, they themselves can ask the ICC to look into violations of the Geneva Convention in Occupied Palestine, and there are numerous such violations, especially in East Jerusalem where Jordanian law was replaced by Israeli law (against Geneva rules). If and when Israeli officials are indicted, the international atmosphere (even in the US) will change. This is only one road to ending the occupation.
Netanyahu: Most of Americans see eye to eye with Israel on dangers of Iran deal (Haaretz)
from the article: Obama can make peace, but mustn't force a final deal