The picture where Putin is a detested psycho hated by everyone including all of his comissars who just wait for a stroke (or bullet) to replace him with a popular, young and charismatic Western-style democratic leader — that's nothing but a conspiracy. And as far as conspiracies go — and as much as that conspiracy is depressing — that's actually an optimistic one. Look, something happens to Putin, and we can have a revolution! But the reality is an even more depressing thought. And the reality is that he has both the elites' support and popular support.
You're building a strawman. We can't expect democracy after Putin is gone, but we can't also expect the same situation we're in now. Putin was an exceptionally strong leader, but part of that role is pruning all possible strong competitors, which usually means that a weak leader will succeed him. The good thing about weak leaders is that it's difficult (and personally risky) for them to mobilize a country for a new war, even if they're more psycho than Putin. As you say, Putin has a lot of support, a new random person will not just magically inherit it just because they're now the president.
> a new random person will not just magically inherit it just because they're now the president
How do you explain that Putin, who was virtually nobody, was nominated as a prime minister in August 1999, declared Yeltsin's successor in December 1999, and then was elected as the president in March 2000, less than eight months after the broad populace first heard of him? How do you explain that the Kremlin nominates a governor, the populace who (at times) never heard of that governor comes and votes for him?
Russia doesn't work the way Western democracy does.
Putin's Russia is nothing like that and Xi's China is leaving that pattern as well. Putin is an absolutist leader with no checks in place.