And replace him with who exactly?
Putin came to power in the teeth of a catastrophic economic situation where piss head Yeltsin's wild west version of capitalism - which greatly benefited western economies - had collapsed and Russian wealth, banking, power, industry, resources had been taken over by a handful of murderous oligarchs. When people talk about Putin's enemies, that's who they're talking about. He's played a complex game of cat-mouse with them since but you really don't want any of them in charge. Likewise you don't want any of his heavy henchmen seizing power.
People talk about how he's a Kremlin man and yes he uses the old soviet mechanisms in his many multi-layered power struggles but how power and influence works now in Russia, with vast amounts of wealth concentrated in few unaccountable hands and everyone plotting against each other, is more like an Imperial Court.
Of those actors, Putin at least is capable of looking outwards and giving the west what it needs. Indeed until he started getting too ambitious and creating a strong economic entity with China, western politicians were very happy with him because his foreign negotiations were favourable to them.
Without him, as things stand now, it all falls apart.