My guess is that both sides will tentatively agree to some de facto borders but not de jure borders. If it brings the fighting to an end, it would at least be a start.
Here are the Instanbul Protocol terms from the 2022 negotiations:
The parties’ desire to resolve issues related to Crimea and Sevastopol shall be committed to bilateral negotiations between Ukraine and Russia for a period of 15 years. Ukraine and Russia also pledge not to resolve these issues by military means and to continue diplomatic resolution efforts.
More from Istanbul Protocol terms from 2022:
These international security guarantees for Ukraine would not extend to Crimea, Sevastopol, or certain areas of the Donbas. The parties to the agreement would need to define the boundaries of these regions or agree that each party understands these boundaries differently.
More:
Ukraine vows not to join any military coalitions or host any foreign military bases or troop contingents. Any international military exercises would be possible only with the consent of the guarantor-states. For their part, these guarantors confirm their intention to promote Ukraine’s membership in the European Union.
“My guess is that both sides will tentatively agree to some de facto borders but not de jure borders. If it brings the fighting to an end, it would at least be a start.”
Not really, as it means that the war restarts in a few years, this time with Ukraine in NATO. If Putin has to settle for that short term outcome, he’ll have to first take Odessa, at least if he doesn’t want to see a firing squad in Moscow. So, probably another 2 months to 1 year of fighting, depending on how much support the US gives Ukraine.