The debate about 2-states, 1-states or 10-states for solving the conflict between Jews and Arabs is for all practical terms, useless and the best term for it is كلام فادي kalam fadi. It takes place in a rhetoric debate club, the only participants of which are Jews. Because it is a pinnacle of apartheid Arabs are not allowed, or unwilling to enter it. As in most of such clubs innovation is not permitted. The participants are allowed only to yell, or rather bark, as if they were Pavlov dogs, the well worn cliches.
UN 181, which called to divide the British Mandate reduced territory into two states, a Jewish state and an Arab state. The territory was reduced because 70 or so percent of it was granted as a consolation prize to the Hashemite family for being driven out of Saudi Arabia. This region torn from the original Eretz Israel, or Palestine was called initially Transjordan, an emirate, later to become kingdom, Jordan.
The tiny area which UN 181 dealt with had both Jews and Arabs living together in many parts of the land. It was impossible to draw a border for ethnically pure Jewish and Arab states. The solution was that the Jewish state will have a minority of Arabs, and the Arab state a minority of Jews.
Such solution is still useful today, again not because of principles, but because of practical reasons.
Politically, it would be impossible for any government in Israel, whether "right," or "left." In fact, for a "left" government the obstacles would be much greater, to move the settlers back into pre-67 borders, by sheer force.
If the principle that Jews can stay wherever they reside as citizens of new Arab state is agreed upon the state of affairs will become much simpler.
Most of the settlers would choose relocation to Israel. Some will not. Judaism, contrary to Islam, is not a political religion. You can be an observant Jew, even a righteous, a Tsadik in Alaska or Kamchatka too. Jews are indeed required to live, if possible, in the Land of Israel, but a Jewish secular state has no religious preference in comparison to any other state. Before the WWII the most ardent objection to Zionism among Jews came from the orthodox. Even today one can be an Israel hater like the Satmar followers, and still perfectly respected religious Jews.
Still, the fact that settlers will have the choice of staying or moving will make the relocation much easier.
The Arab state, if it doesn't want to have many Jews as citizens would support exchange of territory so that the main settlements will become a part of Israel. Even some of Arab towns which are now a part of Israel, and its residents become the most zealous Zionist, reciting day and night Hatikva in Hebrew, Arabic and Russian, whenever exchange of territory is mentioned, might change their mind. If Jews are willing to live there, it can't be that bad.
Jewish minority in an Arab state will transform it into democracy; Arabs will demand the same rights Jews have. Freedom of speech and human rights will become the law of land. In addition, apart of peace, Jews will most probably bring new economic success.
The objective of most supporters of 1-state is destruction of the Jewish state, but even so, it would be hard to claim logically that 1-state is preferable to two, each with minority of the other. Arabs will be never able to create their national and cultural home together with Jews.
Two states, each with a minority of the other, as any other scheme will not solve the conflict, but such idea may have some value for the Jewish debate club.