(1) You're assuming Putin is trying to create a greater Russia. There is no evidence for that yet. Putin has been pounding the table about security guarantees. The Ukraine terrorism rhetoric seems mostly to gain popular support within Russia. In that video, Mearshiemer posits that Russia will level Ukraine in the process without intent to occupy it properly... what are we seeing now?
(2) The sanctions have tons of carveouts and are still toothless. We need more.
(1) I'm assuming nothing. In the context of the quote, Mearsheimer was directly stating the impossibility of an invasion of Ukraine by Russia. He has said as much on multiple occasions since. He was wrong. Period. Much of his political theorizing around Russia goes out the window with that assumption. For example, The West arming Ukraine was inarguably correct at this point. Ukraine is using those weapons to defend their sovereignty as we speak. Did that heighten tensions? I guess. Does blocking your face when someone punches you heighten tensions? I guess. Stating as much isn't exactly novel.
(2) Agreed. Keep an eye on Russian currency markets come Monday. Between removal from SWIFT and freezing central Russian bank assets, significantly painful sanctions are ramping up. The conflict has only been ongoing for 4 days.
"Putin again is much too smart to do that... what Putin is doing is he's basically in the process of wrecking Ukraine and he's telling the West in very simple terms you have two choices: you either back off and we go back to the status quo ante before February 22 2014 where Ukraine is a buffer state or you continue to play these games where you try and take Ukraine and make it a Western bastion on their doorstep in which case we'll wreck the country."
Well, for (1) there's that weird exchange where Russia's spy chief says/slips his (shaky) support about the entry of Donetsk and Luhansk to the Russian Federation before being corrected.
(2) The sanctions have tons of carveouts and are still toothless. We need more.
(3) Russia /has/ been sewing divisions in the West. Politics are extremely polarized in the US in part do to Russian troll farms. Have you seen this nonsense? https://twitter.com/Liz_Cheney/status/1497613102765907968