One Palestine is not a recipe for a stable state imo. You can deport the settlers back to their countries of origin, at least the European ones, but that still leaves a sizable contingent, something like two million IIRC people/descendents of people who migrated/were forced out of the neighbouring Arab states.
You have the Palestinian Arabs in Israel, a great number of whom have, at least to some degree, been complicit in the oppression of those in Gaza and the west bank. On top of that, they are considerably more materially wealthy and educated. Wealth redistribution could fix this, but would create resentment. Not doing so would create resentment on the other side.
You have a rift between the secular and non-secular populations, significant differences in beliefs and politics between the west bank and Gaza, you have secular socialists and zealous theocrats, all militarised (by necessity and justly, but militarised nonetheless).
A two state or three state solution is not just, but even with Israel destroyed, could a one-palestine survive even briefly?