How long do you think Ukraine can hold out? I'm thinking two weeks max assuming nobody else joins the war officially.
From what I've read Ukraine had most of their military staged in the region of the breakaway states. That means the majority of the Ukraine military are more or less surrounded already. How long can they hold out as an island in the midst of a sea of Russian troops?
At this point I legitimately don't know. Two weeks ago I would have said 96 hours. Now?
Ukraine is doing the correct stuff. They pulled their armor formations away from the Russians after the first clash, and have denied the Russians the ability to pin them into a decisive battle. They appear to have spent almost a decade prepping the battlespace, including usable logistics caches, and are using that preparation to enable small unit operations that are very effective. They have let the Russian lead echelons penetrate pretty deep into their territory (trading land for time) and then have done a decent job of compromising Russian logistics in the Russian rear area. They have a well organized and decently equipped reserve force that are being kept in their villages and home areas, so they have both motivation and homefield advantage, and those forces are being told not to engage front line enemy units, which expands their longevity significantly. Ukrainian C2 seems to be largely functional. While they don't have air superiority, they have denied it to the Russians allowing the Ukrainians to continue with (limited) strike and ISR capability.
The Russians have also gifted the Ukrainians by deciding to encircle and shell cities, as not only is that a PR nightmare, it provides a readymade infantry battlespace. Russian AFVs and Tanks will not be able to maneuver freely in heavily damaged cities, and once they dismount the Ukrainian infantry, both regular and irregular, have proven to be very competent. I suspect they are preparing defensive positions in those cities right now.
So, as is often the case, it will come down to logistics and morale. Morale side, I think the Ukranians are clearly more than willing to fight, even to the destruction of large swaths of their country. They are building themselves a mythos in real time. Conversely the Russians seem to be pretty cynical about the whole "De-Nazification" thing and are only there because they have to be.
On the logistics side, the Russians are at the end of a medium length supply route, the last bit of which runs through unsecured territory. They have a massive *expletive deleted*it ton of fuel, ammo, and probably food, the question is do they have the assets and ability to deliver it. That requires a bunch of trucks that work, some infantry to defend them, and the extra fuel and food to move them.
The Ukrainians are receiving supplies from NATO, and pretty clearly have significant supplies on the ground in distributed areas. I don't think anyone knows how much, because as far as I know we didn't know they had done this prep.
If the war stays like this, it's a question of weather the Russians lose the ability to supply fuel and ammo to their troops before the Ukrainians run out of ammo and man portable AAWs*. If the Russians manage to pin down a couple large chunks of the Ukrainian military, they are likely to defeat it, and that might push the war to their win. I think if the Russians try to enter and take the cities they are currently encircling, I think the Ukrainians will be able to kill enough of them in urban fighting to force Putin to back off. 10,000 or so dead Russian boys is something even Putin can't hide.
Again, the big unknown is Ukrainian supply status. They were clearly way more prepared to let this drop into a small unit irregular war and to strike at Russian REMFs while paying the cost in buildings, civilian dead, and infrastructure destroyed then anyone thought. Since we didn't know they had prepared the battlespace at all, it's hard to guess how well they did it, but just from Russian movements, confirmed destroyed and damaged vehicles, and the lack of any large scale engagement it's pretty obvious that it's going much closer to the Ukrainian plan than the Russian one.
Also Ukrainian PSYOPS has been masterful, while Russian has been pretty heavy handed Soviet style and ineffective.
*ETA: Anti Armor Weapons. Sorry, sometimes the acronyms slip out.