I think it is crucial when discussing Israel's "right to exist" that it is understood what is meant by that when the question is asked. First of all, the "right to exist" is not a legitimate term in international law. In other words, no state demands the right to exist and no state's existence is recognized under international law. In terms of peace proposals, Palestine has always been in favor of a settlement that would guarantee the existence of the state of Israel in exchange for mutual recognition - a proposal that is supported by practically every country in the world and historically rejected by the United States and Israel. If one looks back at the diplomatic history, they will find that Israel shifted their position when the PLO and the Arab states supported the two-state settlement solution and that shift was characterized by the "right to exist", which meant that Palestinians would not only have to support a solution that would grant Israel statehood (since they already supported that) but, rather, have to acknowledge the legitimacy of the state that dispossessed them from the land. I'm not sure who would support that, nor is there any reason to argue that Israel should be above the standards of international law.