Treaty etc
As others have said above, if Russia is allowed any gain from this, any cessation of hostilities will be worthless and last until Putin et al decide oterwise. What concerns me is the resolve of western governments to get stuck in and throw everything necessary at this to stop it in Ukraine's favour. As we have seen recently in the UK and elsewhere, domestic considerations incentivise politicians to take the easy line. I have yet to hear one make a convincing case for us all enduring hardhsip in order to fix this problem once & for all.
Without that resolve I can see stalemate, a fudged treaty and here we go again in 5 years time