There is often an effort to equate a leader of a country to the country. “Putin is a madman” and similar ideas put forth the concept that removing a leader end an issue.
Of course, this is wrong. JFK was murdered and LBJ continued to escalate Vietnam. FDR died and Truman continued fighting WW2 and dropped the atomic bomb.
Trump may have been “different”, but he continued a lot of US policies, including increasing arms shipments to Ukraine and supporting Israel. He did change some foreign policy issues such as dumping the Iran Deal, improving relations with the Saudis, confronting China, and almost solving the North Korea issue. Trump was very limited by a government full of bureaucrats that had their own agendas, so changes often
British historian A.J.P. Taylor argued in one of his books that Hitler leading Germany acted not as some odd aberration but in continuation of German policies. There are some limits to such arguments, but Hitler definitely was in a line from Bismarck and the Kaiser and followed through on earlier ideas and plans.
All leaders at every type of organization must balance interests and followers. A king, even one like the Sun King, must tread carefully dealing internal factors as much as more than external ones. Going against the character of an institution or organization will often lead to friction and problems.
Trump was a great example of why radical change is difficult in the short-term. Every deviation from acceptable DC narratives brought increased resistance. This is why Obama mostly extended Bush's policy, foreign and domestic, changing only slightly.
Trump didn't learn the lesson of Machiavelli, that anyone trying to start a new regime and make changes needs to go hard core cleaning house.
Machiavelli's The Prince is the classical work about governing for a reason. The principles set forth therein are true whether or not we think they are good. It might seem bloodthirsty or cold-hearted, but it is reality.
A modern take on this is the work, The Dictator's Handbook. It is a modern take on the subject, back by research, and not just about or for dictators. I might do a book review later, so well as for the Prince. For those that want an audio-visual version, the Netflix series, How To Be A Dictator is based on this and features the author.
So let's get back to Putin. Putin is not a dictator. He does not have absolute authority. And Russia is not the same as Putin. Putin has to be concerned at satisfying his allies and supporters, and preventing an opposition from gaining ground. Putin became Russia's leader because of US support. Kissinger and Clinton signed off as him. He was seen as very Atlanticist. And up to 2008, he was very supportive of NATO an wanted Russia included.
Putin also struggled with extreme nationalist elements in Russia. Until recently, they viewed Putin as too Western, too accommodating of the West. In some ways, that criticism was true.
Part of the reason for the Russian military operation in Ukraine was to placate internal Russian factions. These people are firmly behind Putin today, but they are concerned about a too early end of the conflict that doesn't reach the goals they want. Putin does need to make sure any end of the conflict is enough to placate these forces.
If Putin dies tomorrow, Russia will continue the conflict and may expand it. Putin’s successor will likely be less reasonable.
Independent of anything else, a future leader will likely continue the separation of the BRICS and their allies from the West. Again, Putin is Russia and any future leader will only make changes slightly from the past policy. The structure and culture will resist major changes.