It would recognize that post-1948, a trade was achieved between the expulsion of 600K Palestinians from west-of-green-line Israel, and the expulsion of 600K Jews by Arab states. Both were horrific crimes, but are a fait accompli, and are at least symmetrical injustices. Any population movements after that are asymmetrical, and should be compensated. Unfortunately, Israel will never relocate 400K settlers, nor will it accept 400K Palestinians. Look at the furious opposition in these comments.
U.K. is offering 4,000 resettlement spaces for Syrian refugees, UNHCR spokeswoman says (Reuters)
from the article: Peace Plan: Trading settler Israelis for refugee Palestinians