Clark retired from the Army in 2000. His thinking is very out of date and he doesn't seem to understand the Psychology of Ukraine. Mark Hertling and Ben Hodges are also retired generals, but they were both involved in training up the Ukrainians in NATO tactics.
Clark seems to think that Ukrainian people are suddenly going to pivot and demand peace when they have done nothing but give Russia the rudest salutes in 9 months of war. Ukraine is like the poorer spouse after a messy divorce when asked by the wealthy ex if they would come back and the poorer ex replies that they would rather live in a dumpster than spend one more minute with the rich jerk.
Ukraine is completely and utterly done with Russia. It doesn't matter how much damage Russia does, Ukraine is not going to quit. Any damage Russia inflicts at this point just makes Ukraine more determined to finish the divorce.
The entire world that has been adversarial to Russia for some time sees that this is the opportunity to neuter them pretty much forever. Russia lacks the domestic industries to rebuild their military to anything close to what it was before the war. It's chemical industry is much weaker than the USSR (a lot of their chemical making capability is now in other countries). They can only make a fraction of the building blocks needed to make ammunition and rocket fuel. They can make some (though their biggest chemical factor burned down six months ago), they can't make ammunition anywhere close to the current burn rate.
They lack the electronics industry to make the ICs they would need to control their smart munitions. The critical electronics they need to make smart weapons came from Germany. They can get some on the black market, and apparently one of the microprocessors they need are commonly used in washing machines, but those are limited sources. Removing surface mount chips from circuit boards to install on another board is risky. The part can be damaged removing it. Those parts are not made to be removed.
They have a small class of trained engineers, programmers, and technicians. A large chunk of that group left the country when the war started and they aren't going home anytime soon.
Russian military isn't as good as Soviet metallurgy (and the Soviets were behind the west). The can't make good quality, new gun barrels. As their artillery wears out barrels, the guns are tossed aside and the newly manufactured guns (very small quantities) have softer barrels than the guns they replaced. So they will wear out even faster.
Sanctions are beginning to bite. There are many parts for industry that are only available from western suppliers. The Chinese don't make equivalents for a lot of these things. As that tech wears out, they can't get spares. They move their oil and gas in very long pipelines with many pumping stations. As those pumps fail, they will lose the ability to get oil and gas to world markets.
Their oil industry is also very dependent on western oil company expertise to keep the fields in working order. Any work needed to drill new wells, turn fields into secondary production as they get older, etc. are not happening. Back in the mid-90s my sister's Geology company got a sub-contract from a US company helping the Russians rehab the fields the Soviets had run into the ground. Her company was digitizing a lot of well log data, but she talked a lot with the people who had been in the ground in Russia. Nobody was impressed with the quality of Russian oil professionals.
That was 30 years ago and maybe they improved, but there are a lot of western oil people who were working in Russia before the war and many have left.
If the sanctions remain on Russia the country is going to slip into 3rd world status. They have had a massive brain drain and they son't have the domestic industries to recover. China is still doing business with them, but China doesn't make a lot of the technologies they need. China is an industrial giant, but they don't produce many cutting edge technologies like the most modern integrated circuits, and their advanced metallurgy is limited too. China was only able to figure out how to make the balls for ball point pens about 10 years ago. They are just now beginning to be able to produce some jet engines that are on par with what the leading aircraft manufacturers can make.
China also doesn't want to put their biggest markets at risk. Russia is a tiny market for them while Europe and the US are the bulk of their trade. If they have to choose one to drop it will be Russia.
China also doesn't want to see Russia succeed. If Russia falls apart, China can indirectly control all the new countries in eastern Russia, which will be a huge economic boon for them.