And soon they’ll get to know the pain of rooting out/assaulting dug-in, modern forces.
They will burn through men and equipment as the Russians did.
Maybe... it could happen, but that's not what happened when Ukraine defeated Russian forces around Kiev, Kharkiv and Kherson.
In those examples, Ukrainian forces moved rapidly, panicking and surrounding fleeing Russian forces.
Will that happen a fourth or fifth time?
There's no way for us to know, but I would not underestimate Ukrainians, or overestimate Russians.