Justin Bronk of the Royal United Services Institute gives a painfully detailed analysis concluding with the observation that it’s hard to see how Russia can keep up the pace militarily for more than a few weeks. The video below shows the conclusion of the discussion. Rewind to 45:24 to see the start of the discussion:
Later edit: Well as of July 2022, Russia’s still going. So this prediction was off by at least an order of magnitude.