they may just end up dead, or retreating to Ukraine, I wouldn't imagine Ukraine turns them away. But it seems like they are trying to give themselves the most defensible position they can. it sounds like they picked some natural borders to keep the Russian's at bay.
Doesn't sound like they plan on expanding, because that border works both ways.
I will be interested to see how both Ukraine and Russia handle this. Does Russia try to crush it quick? I would think that would be the typical thing to do. They MAY try some diplomacy at first while they bring up forces to the area. Revolution has a tendency to spread if not quashed quickly. Other dissidents may decide to test things out too if they see this BMR stick around for a while.
then does Ukraine try to push in and take it, or do they think its a trap/not worth it? Having some defensible grounds inside Russia would be a pretty big win, at least as telling as Bahkmut was. or do they let them be martyrs to Russian tyranny putting the truth to the lie about this whole operation being out to protect ethnic Russians.