To be clear, I think people have been somewhat harsh on Mearsheimer, there may be a discussion to be had about how we got to this point, even if I don't agree with his view that it's all US driven.... but, contrary to the "this guy was right the entire time" line, he's been pretty wrong on the actual invasion and everything that has transpired since.
Putin did do a full scale invasion, Putin did try to take Kyiv, Putin's aims went beyond theoretical NATO membership for Ukraine, and the cultural and linguistic ties to Russia didn't cause Ukrainians to lay down arms... if anything, from what has been reported, it has only caused Ukrainians (particularly those in the east) to reevaluate their views on Russia.
EDIT: And on the last point, Yaroslav Trofimov (who has reported for WSJ on the ground in Ukraine) was asked about that question on a Reddit AMA yesterday, and, IIRC, he seemed to suggested that the damage that Russia has done will take multiple generations to fix.... on top of Putin needing to be gone.