The other question is: Once Prigozhin ordered his army to turn back, having realised he lacked sufficient support in the regular army and the security forces to become the new king-maker, why wasn’t he arrested and shot, or at least thrown into Russia’s deepest, darkest dungeon?
The answer to both questions is that these events occurred because Putin is far weaker, and his power much less secure, than anybody suspected. “Anybody” includes Putin himself, in all likelihood. When he pulled the levers of power, it turned out they weren’t connected to anything.
Imagine, for a moment, that a very large convoy of heavily armed rebel militia left Chicago one day during the Vietnam war, heading for Washington with the announced goal of getting rid of the Defence Secretary and the Chief of the General Staff. Why? Because they weren’t good enough at killing Vietnamese, and the war was being lost.
Would that column have made it all the way to Maryland before it was stopped — and stopped even then thanks only to the intervention of the Canadian prime minister, who talked the rebels’ commander out of seizing Washington and gave him asylum in Canada?
All analogies are imperfect, but this one is serviceable enough. It tells us the current Russian state is a ramshackle structure that has little in common with modern great powers like the United States or China, or even with the Soviet Union or imperial Russia between the reigns of Peter the Great and Catherine the Great.
Today’s Russia is an aggregation of private fiefdoms with few loyalties beyond the personal. The army, despite its extreme corruption, is the only large Russian organisation that sometimes (but not always) acts in the perceived national interest. And the army conspicuously did not intervene to protect Putin from Prigozhin’s anger.
What saved Putin was Prigozhin’s recognition as his armoured column neared Moscow that the army, while not defending Putin, was not rallying to the Wagner leader either.
This is the chronic problem with coup plans: the requirement for secrecy means that the plotters cannot accurately measure the potential support for their plans before they act. Prigozhin’s troops could probably have taken Moscow, but they couldn’t hold the whole country, and the result could well have been civil war.
Prigozhin is a thug, but he is also a patriot. Not wishing to be remembered as the man who unleashed a civil war, he started looking for a way out — and grabbed at the deal that Lukashenko offered him.
Conclusions: Putin is so badly weakened that he may be gone as soon as those around him can agree on a replacement. However, they would be wise to wait and see if the Ukrainians make big advances, as defeat in Ukraine could then be blamed on Putin.
Any replacement will also feel compelled to pursue the war in Ukraine. The outcome will still be dictated by the course of battle.