Ukraine is holding because it's still being dripfed weapons and money by the remaining partners it has. If it dries up they will be steamrolled. Probably not immediately but it will become bad for them very quickly
One way it could dry up is to distract NATO or eu countries with a defense treaty, by something that feels like a real war but not serious enough. Enough that those countries finally say "Oh shit, no more weapons for UKR now we really need to bolster our own flank"
Then Ukraine falls and their 1 mil. of well experienced soldiers get force-conscripted into Putins army and Europe has a problem
One way it could dry up is to distract NATO or eu countries with a defense treaty, by something that feels like a real war but not serious enough. Enough that those countries finally say "Oh shit, no more weapons for UKR now we really need to bolster our own flank"
Then Ukraine falls and their 1 mil. of well experienced soldiers get force-conscripted into Putins army and Europe has a problem