I would just offer that the GRU, the SVR and the FSB have a different loyalty complex in play than others, so they're the internal security apparatus that is directly responsive to Putin. The likelihood of an external change, absent some sort of a “colour revolution”, is less likely because of those entities. It's more likely that it would just get really complicated for Putin, and he ultimately gets replaced for all the reasons that Maria outlined.
On February 28th, 2022. See this statement in context.