There was literally never any chance that Ukraine was going to cause the fall of the RF. That's absolute cope. The USA, through NATO, was attempting to boil the frog (Russia) and Russia appeased the US for 20 years before reacting to Euromaidan by annexing Crimea. The US decided to call Russia's bluff and continue developing NATO's position in Ukraine for the subsequent 8 years and Russia warned and warned and finally attacked to disrupt the process. Russia successfully disrupted the process. The USA's goal was to deploy it nuclear capabilities and requisite logistics to Russia's most vulnerable border. Ukraine had no goals of harming Russia, only pleasing Western masters so they could be let into the imperialist club and their oligarchs could benefit economically and politically.

The greatest risks to Russia after they launched the SMO were 1) allocating too many forces to the front, leaving them vulnerable to attacks from the West in other locations, 2) exposing too much of their capabilities and capacities to Western intelligence, and 3) being unable to handle the activation of potential long-term sleeper cells cultivated by the West.

There was never a risk that Ukraine itself would collapse the RF.