Putin was brought to power by a clique and that same clique will have succession ideas in mind.
Yup and that clique are now entirely reliant on Putin’s power structures for their (immense) wealth and protection.
Of those that put him in power, the ones with the charisma and leadership potential to replace him have been sidelined, jailed or exiled and the rest, enfeebled by years of nepotism and comfy living, are now reliant on the system that revolves round Putin.
Putin has deliberately made himself the keystone, if he wasn’t he’d have been challenged already. If he goes everything crumples. He knows this and those under him know it.
Medvedev wouldn’t last 6 months without Putin’s patronage behind him.
All in all great for Putin, not so good for Russia, but that’s Putinism neatly summarized.