The exact borders are likely to be what Russia thinks of them now, 4 oblasts. As for the rest of the territories, there's more complex situation. This is a war of attrition and Russia isn't going to back up as hostile Ukraine is existential threat to them, while Russia in Europe is a threat to liberalism and the EU.
American strategy
With what Trump doing, he's only goal is to get money from that conflict and be seen as a good guy. He already demanded Europeans to pay for the new weapons and got concessions with Ukranian government. As soon as inevitable deal is to happen, Americans will, probably, try to 'barter Ukraine' for other things from Russia, like keeping the rare earth element concession or keeping Israel safe from Iran and Iranian proxies.
The other story is to be told if the conflict doesn't end in the next 4 years when another president will come to power in the US. Maybe, we'll see a democratic globalist, no one knows for now.
European strategy
Unlike Trump, Europeans are existentially interested in keeping Russia away from them. And they are truly afraid that Trump will leave this conflict, as they wouldn't be able to continue supporting Ukraine on the same level (as for 2024, most of the support was from the US). That's why we see talks about the coalition of the willing, creating a European army, reviving military industrial complex, returning compulsory military service, and so on. (That will also be helpful to keep the EU together, check Fukuyama's 'More Proof That This Really Is the End of History' essay) I, personally, doubt they will be able to do all this in time (you need at least 3-5 years to revive military industrial complex) and have the nuts to actually get their army to Ukraine. That's why they will have to make deal with Putin, and their aim will be to get the rest of Ukraine under their influence, probably, by enacting new Marshall plan and ensuring that central government of Ukraine will be strong enough to keep the situation in regions stable. They also want to get their peacekeepers there, but that's unlikely as it is Putin's primary goal not to have any NATO soldiers at his doorsteps.
However if they will be able to build up their support in time, well, all quiet on the eastern front. The war continues until Russia or Europe won't be able to keep fighting.
Russian strategy
This is a war of attrition and sooner or later there'll be a peace deal, Russia sees the hostile Ukraine as existential threat and won't ever back up because of this. Moreover, for Russia the real meaning of the conflict is not about getting land. As Russia has its interests far beyond Ukraine, they see that war as 'war of independence' from the West. Anyway, the fun part begin the moment Ukranians and their allies agree on some sort of concession, just like Germany during WW1 agreed on armistice of Compiègne, they won't be able to continue fighting after that. Today Ukraine's constitution have to be changed to fullfil Russian demands that they see highly necessary since the start of the war (neutrality). The Russian aim will be to make subtle changes in the new constitution - to give right of oblasts to leave Ukraine, just like other 5 oblasts did, according to Russia, and leave the central government without much taxes from regions. After that, in no time Ukranian land will become effectively a wasteland, unless someone will give much resource for its recovery. Russia won't give resources, unless they join Russia, and the European (new Marshall plan) and American influence will be limited after neutrality declared.