Well, the outnumbered American Patriots won the Revolutionary War in 1781 by encircling 8,000 British troops at Yorktown (whose exit was blocked by French ships, and were forced to sue for peace).

Another encirclement of perhaps 25,000 Russian troops, along with renewed support from victorious Western politicians (starting with Harris and maybe another $100B) might force an end to this conflict. Perhaps in all the land swaps, Russia would keep Donetsk and Crimea only. Otherwise, this thing could go on for a long time.