I would laugh for days if Ukraine crushed Russia militarily but I really don't see it happening. I think Ukrainian military defeat is a foregone conclusion and we shouldn't draw overly optimistic conclusions from the botched invasion. Especially when it comes to Russia's performance in a hypothetical full-on regional war. It would not be the first time that people drew erroneous conclusions about Russia's large-scale capabilities from a boondoggle invasion (I'm talking about the winter war of course, which played into Hitler's confidence about an invasion, also of course relevant to note that despite their disproportionate performance against the Russians Finland lost the winter war)
There's ample reason to believe that the forces Russia has already committed to this war constitute
everything usable that they have.
The spread of equipment known to have been deployed and destroyed ranges from "most advanced model currently in service" to "factory-standard and unupgraded models from nearly fifty years ago (there's been some stock T-72As (which rolled off the production line in 1979) confirmed destroyed)". That's where the completely nonsense conspiracy theory that "Russia is just sending in all their crap troops to soften the Ukranians up" comes from, because nobody wants to admit that the Russian military is in this sad a shape.
On paper, Russia still has immense reserves of men and equipment. But this war is such a perfect example of the difference between "paper strength' and "actual strength" that it could be used as an academic dissertation. Even if they actually have the men they claim to have (which they probably don't - lack of manpower has been a critical issue for the Russian armed forces even in their "interventions", which is why they rely so heavily on groups like Wagner), they're very clearly critically short of fuel, ammunition, and up-to-date weaponry. It is blatantly obvious that their huge piles of mothballed equipment have not been maintained properly (many of the photos of abandoned vehicles show obvious signs of failing seals and such), their new weapons don't work, and they're running out of trucks.
Meanwhile, the Ukranians are growing stronger by the day as more and more of the highest-grade weapons in the world (which
do work, as it happens), and have more manpower than they can effectively use at the moment. They're growing stronger by the day.
This isn't the Winter War, or the invasion of Poland, or the Fall of France. This is Mussolini's invasion of Greece (even including the pro-russian activists demanding that the victims stop defending themselves), and there's no Hitler to bail him out.