I think that it's a red herring. Settlements were evacuated in Gaza, it led to more terrorism, not less. There was also more than enough terrorism before the first settlement was ever founded. There are 700K Jews living in Judea and Samaria, they're not going to ever be evacuated anyway unless as part of an ethnic cleansing campaign by Palestinian terrorists or something like that.
So all in all, the question of the settlements is one of the least important questions in the conflict.
Ariel is not going to be evacuated, more likely that something like Trump's plan would place it within Israel using complex and convoluted borders, and the Arab "Palestinians" will get territory elsewhere as compensation (again, similar to the Trump plan).
Well, I still think that it was a good thing to evacuate Gaza because it put Israeli soldiers less in harm's way. When they had to occupy Gaza, they were in close proximity to over a million angry Arabs while defending less than 10,000 Jews. (Though honestly I think that Gaza should ideally go to Egypt because it needs extra space due to it being overpopulated as Hell right now!)
In theory, Jewish settlers deep in the West Bank could become Jewish citizens of a future Palestinian state, but they would probably want to have their own weapons for self-defense just in case in order to protect themselves from the risk of angry Palestinian Arab mobs.
I don't see the Palestinian Arabs or for that matter the rest of the world ever accepting anything comparable to the Trump Peace Plan. At best, you might be able to get Ariel as an Israeli enclave within a Palestinian state, along with perhaps Kiryat Arba near Hebron as a separate Israeli enclave. A good map would look something like this (except perhaps with the enclaves mentioned above and also with Israel including E-1 in the Jerusalem area):
A Stable Border- Proposal for land swaps 2020 Annapolis 2008 Israeli Proposal Annapolis – Israeli Proposal – Jerusalem Annapolis 2008 Palestinian Proposal Annapolis – Palestinian Proposal – Jerusalem Taba 2001 Israeli Proposal Taba 2001 Palestinian Proposal Camp David 2000 Israeli Proposal Camp...
I personally wouldn't want to keep the Arab parts of East Jerusalem either, especially if they have no religious value to Israel and Jews, due to the fact that these areas would simply be a welfare sink for Israel.