Ukraine is most likely done in a matter of months if the US pulls out.
Doubt it. Peace deal contingent upon many factors if we assume Trump does what he says (and a large part of his mandate, among his hard base, comes from this).
1. Russian territorial claims. I don't expect Russia to cede anything to the east of Crimea now whereas that was, imo, entirely possible two years ago when peace negotiations were being touted briefly. But Trump may get that which is to the West.
2. Security Agreement which becomes a trade agreement. The unfreezing of Russian assets in return for quid pro quo elsewhere (territorial most likely). Also, full access to the American market and negotiations regarding American access to the Russian market. This is not small. Russia (and BRICS are in on this in the longterm) has, because it was sanctioned, moved away from all the international brand names (someone may fact check me if I'm wrong here) and it's an interesting conversation regarding what chunks of the Russian market are up for "free trade" again if a peace deal is signed.
2.(A). Russia will not accept Nato presence in Ukraine. It must, however, (and here all peace deals fail if Russia refuses), redraw its demand that Ukraine be "de-militarized". That is never going to happen considering what has happened over the past two years.
(B). EU role within this security framework as was being discussed before Russia invaded within the Normandy format. EU states will want assurances even though I'm absolutely certain that not one of them believes they are in any direct line of threat, except if the war continues, at all. Everyone here will disagree with that. History will settle the answer.
3. Ukraine entry to EU. Russia doesn't oppose this (last I checked and I've been avoiding this war for good reasons, personal) at all. It said so two years ago.
3(A) Reliability of the Ukrainian market (whatever its territorial make-up, see [1]). America has pumped >270 billion into Ukraine. It wants its money back and with a profit. It can only do this through peacetime share of the Ukrainian economy. This goes back to the security agreement but it is in the EU's (billions, also) and US's interest (purely financial, now) to see some form of Ukraine emerge which receives stimulus from both the EU and US. This will likely be a neoliberal post-War boom for Ukraine and an eventual disaster which all nations are used to at this point as neoliberal policies create "wealth" (or its illusion) at the outset but then, when all is stripped, it becomes a parasitic false monopoly (where the US/UK basically are now, some EU nations not far behind). A different discussion.
tl;dr
I stay out of this thread because I don't want to rile anyone up but am only commenting here because the US will sue for some form of deal but it will not be like Vietnam where the helicopters left with people hanging onto them. It will be a settled negotiation. Only way it ends anyway. (As I said, Russia will not lose militariliy as many of the top US brass knew many years ago regarding its border dominance and the US as well most of the world knows this). This irritates people, I understand, and that's why I won't answer back to comments (so as not to keep an irate discussion continuing). Just wanted to point out that scenarios of Ukraine being left like Vietnam (in the US leaving and not giving a feck) is very wide of the actual mark.
Also noteworthy is Trump says he wants to go to Tehran which has not happened since the revolution iirc. Interesting because Russia just agreed to underwrite Iranian security de facto by virtue of their nuclear deal. Interlocking spheres here (geopolitically - bleeds into potential Israeli de-escalation also). We'll see.