I think Ukraine is going on an offensive this spring/summer and they'll go after Crimea to end the war. If the Russians are able to defend, I believe that we will see a ceasefire where the Russians will hold on to the occupied territories of Ukraine and Crimea.
I don't see any possibility of retaking the Donbas and Crimea without NATO boots on the ground.
We can give Ukraine everything they ask for with the exception of more Ukrainians. And Ukraine will run out of fighting men long before Russia will.