Why is Walt conducting a “thought experiment” on what would happen if Jews were expelled from the country in which they live? This in fact happened time and time again in 1948-49, as Jews were expelled from Arab countries from Iraq to Algiers to Yemen. The key is not the expulsion, but the reaction to the expulsion.
When hundreds of thousands of Jews were expelled from Muslim countries in the aftermath of the Israeli War of Independence, they were taken into the State of Israel, at great expense; housed, clothed, educated and trained, and eventually (despite some fairly strong social discrimination against them) became full members of Israeli society.
On the other hand, Palestinian Arabs who came under the control of other Arab governments were not welcomed as brother Arabs and co-religionists, but were installed in squalid refugee camps, used as helots, and ultimately as pawns and cannon fodder against the Israeli state. If there is a Palestinian refugee problem today, the responsibility rests with the Arabs, not the Israelis. If there is no Jewish refugee problem today, the responsibility likewise rests with Israel, and not with the Arabs.