Russia not able to win would look like Syria. Syria is a failed state propped up by Russia and Iran carved up by superpowers with the local population at their whim.
We also dont live in 2000 anymore. As far as i am aware Ukraine didnt get any noteworthy anti air shipments. Stinger are useless for anything except passenger planes and some older helicopters. You wont shoot any jets down with it. And once doctrine switches back to standard artillery bombardment there isnt going to be much else to shoot at.
All of this not mentioning drone warfare and the ability to identify what they deem hostile elements. Russia is only limited in how cruel they are going to get in this. Of course they can win, it could just become very very horrible.
If you think this conflict will look like Titos partisans if escalated further, think more Grozny combined with the treatment of the Uyghurs.
edit: Think about that way, getting rid of everyone who still holds your opinion, that
>Most of them are aware that Russia cannot win. They cannot hope to occupy and rule Ukraine if Ukrainians don't want them to. Why submit then?
after a few months of classical bombardment is by now a trivial task. Same with the larger group who would do something about that. And even if you somehow could hide creating refugee waves is a very attractive geopolitical tool for Russia.
It is that bad.