But I wonder how long it will last before Palestinians start muttering "but this was OUR land, and still should be". You can't kill an idea that easily.

No, not easily. But ideas can be killed, even so. Or at least weakened to the point of irrelevance. Not all separatist movements succeed. History is littered with failed uprisings, abandoned independence movements, and righteous causes that were left behind. It might be much harder to find recruits willing to die for Palestinian independence when doing so means fighting against other Arab soldiers rather than Israeli ones. Or trying to organize in the face of repression efforts like those in Egypt against the Muslim brotherhood.

It will depend on whether the nations that seize control of Gaza actually want to control it or just want to hold it long enough to get their other deals signed and then let it fall into chaos. I think it could go either way. Those countries are far more willing to link arms with Israel and deny opportunities to Iran than they were even a decade or two ago, and if the U.S. is weakening human rights activities against them (both American and otherwise) then they might be content to squelch Palestinian independence in Gaza in order to keep a firm grip on the place.