A hardliner will take power (Putin is not the most antiwest russian politician) and then...from the total erasing of Ukraine to third world war, anything would be posible, but neither civil war nor colapse of Rusia. That is the OTAN countries wet dream.
This is very likely. If anything, the existing system will be perpetuated because there's no replacement atm. It's been too long in the making and it will take a lot of work to undo. Also, he may be long dead and it won't change anything in the near future.
This said there's always a chance for a change, but not right now.
Definitely but that's unrelated to Putin and his direct actions. The OP's question also doesn't mention anything about West right Putin wrong, they are just asking what's going to happen if Putin is no more.
Those kind of questions can not be made without context, it is not a game of words without consequences. If it is a game, just to waste time posting in this or any social network, let's stop here.
It is about a real person, who is a leader, whose murder would spark grave consequences. And that leader actions, like taking the decision of going to war or not, are related to decisions made by other leaders. Right now there is a campaign demonizing that leader, and that campaign normalizes ideas mirrored by that kind of questions. There lots of memes, jokes and things like that asking for Putin's dead.
If i asked, what would happen if Donald Trump were assassinated? Or Biden, or Xi Jing Pin, Erdogan, etc? At this moment when all media are strugling to influence public opinion? It won't be a futile harmless game.
The question is purely speculative. Try swapping Putin for any western leader and then answer the actual question if it helps.
I can speculate easily what will happen if Biden is assassinated because the probability of anything is not zero. The VP will take his place and so on.