Beating the Russian Air Force in the air isn't the primary issue, we can do that. The bigger issue is that a no-fly-zone must be secured, i.e. bombing radar and SAM installations in Ukraine/Belarus/Russia.
> ... they carved themselves a situation where they can't really _lose_, ...
Quite the opposite, what does a Russian "win" look like here? A huge portion of the population doesn't want them there, a puppet government won't be internationally recognized, and the resulting insurgency would make Chechnya look quaint. Not to mention the humiliation that Russia has already suffered.
It's lunacy to think that Russia is gaining anything out of this. It's not even certain that Russia can beat Ukraine anymore, and it's already a pyrrhic victory if they do.