If Russia can get them to give up NATO and EU ambitions, and get them to start supplying water to Crimea, they can sit back and wait until they can claim Ukraine by other means (as they already tried once, and as Belarus has gone). Conceding on that, at this point, is just delaying the Russian takeover somewhat. If Russia can't get that out of them, I expect them to demand such large territorial concessions that what's left will have, at best, 1/2 the GDP it used to (not even counting damage from the war). That diminished state will go on to head toward EU and/or NATO membership, but it won't represent the kind of relief valve from European dependence on Russia that a free and prosperous united Ukraine might (which is a big part of why Russia wants to carve them up or conquer them to begin with).