It's worth returning to the thread topic, which isn't really about a talk given by an American political scientist in 2015. Nor is it about the Russo-Georgian war in 2008. It is about the current crisis in 2021, where Russia is poised to invade Ukraine again. Maybe Professor Mearsheimer holds the same views that he did in 2015, well before the COVID crisis reshaped the global economy, although he may have a different idea of the threats that China and Russia play in the current year. He isn't the only political expert out there, and he is but one of many political pundits in academia who have informed opinions about US-Russia relations.
The latest news seems to be that, despite Putin's denials that he is planning another unprovoked invasion of Ukrainian territory, he has now listed the terms under which he will refrain from doing so. Hopefully, these are just initial demands that he has put out there to try to leverage some concessions from the Western Alliance. He needs some kind of concession to save himself from losing face over a crisis that he himself has manufactured out of whole cloth. Nobody is threatening Russia with an invasion, and he isn't going to get veto power over who can join the EU or NATO. Those are non-starters for any serious negotiation. It would be foolish for the West to try to give either Georgia or Ukraine membership at this point, but Putin likely knows that nobody is really threatening to do that. The US is refusing bilateral talks with Russia for now, but it is willing to meet with other nations that have a stake in the outcome of such negotiations--major EU countries, Ukraine, Russia, and perhaps some Baltic states that Putin has added to his list of demands.
See: Russia Ukraine:
Moscow lists demands for defusing Ukraine tensions