Jordan
“Jordan”
If a deal is structured right, Jordan could absorb a good bit of the Palestinians. Jordanian concerns would need to be addressed.
They have a lot of Palestinians already (1/3 of Jordan’s population), and they struggle to maintain domestic political stability with what they already have. The King’s father had to send the Army in to drive out the disruptive PLO, in the “Black September” event, killing 20,000. The PLO then went on to de-stabilize beautiful Lebanon.
If it is a comprehensive, and broad regional deal, backed up by significant investment, the Palestinian population could be significantly dispersed among neighboring countries.
Egypt might be incentivized to take the Gaza Strip - densely populated with nearly two million. That would likely require a lot of start up capital.
Saudi Arabia and other Gulf Arab States could offer preferential employment opportunities and possibly a pathway to citizenship. 100,000 lucky young, Arabic speaking, Palestinian families could help to jump start the new Saudi City of Neom, just a 2 1/2 hour drive from Eilat.
Palestinians are a relatively urbane and well educated pool for Arab employers to hire from. Other Gulf Arab States could offer alluring scholarship, employment or even selective citizenship opportunities. Israeli companies could help establishing those opportunities throughout the region, and recruiting Palestinian employees.
Of course, as you point out, Jordan is a natural home, which formerly administered the area, and many of the people’s ancestors.
But then, what about the land? The Jordan River makes a clear (and more defensible) boundary. Also, Jordan naturally has deep security and economic concerns, about trying to absorb just the over two million West Bank Palestinians. Building enough new housing in Jordan, building out infrastructure, and providing satisfying economic opportunities would take a decade of serious investment.
If (as I suspect) there is a long term economic development concept to manage the Palestinian population with dignity and opportunity as part of this Grand Deal, then the next phase (2021 to 2024) would be starting to make such major investments (10’s or 100’s of billions of dollars), and to institute new policies (Dubai-like free trade zones, easier employment/emigration opportunities for Palestinians in the region).