By “surrender” I mean limiting military and financial support for Ukraine to a level that would severely limit its defense capabilities, resulting in actual front line collapse.
In terms of outcomes, that would mean Russia executing its rather aspirational plan of reaching administrative borders of the four regions it declared “annexed”.
At this stage Ukraine would be likely forced to comply with Moscow’s 2022 conditions for peace, that is reduction of armed forces, internal legislation changes (Russian language and Ukrainian national symbolics), no NATO membership and legally ceasing the four regions in south-east.
And I don’t think it would happen fast, because Russia has no reserves on its own that would allow them to quickly establish control even against guerilla-style resistance. And I’m pretty sure Ukraine will continue fighting as hell with whatever it will have at its disposal.
Still the critical factor is the sanctions - in case of Ukraine’s defense collapse described above, the Western countries would have no reason to remove the sanctions other than greed of their own business sector. Politically, removal of sanctions only makes sense if its traded for some Russia’s concessions and that’s possible where actual negotiations would take place in this “collapse” scenario - for example, territorial concessions limited to the current line of contact and limited political interference in Ukraine’s legislation.
Disclaimer: this is of course the worst case scenario which I believe is very unlikely, because even if US decides to stop any support for Ukraine the EU and especially Baltic and Eastern European countries have plenty of reasons to do everything possible to make sure this doesn’t happen.