Second scenario is: permanent tension with the West.
(1.) The costs of a military solution to the Ukrainian question are too high. Even in the event of a quick defeat of the Armed Forces of Ukraine, the problem of control of the territory arises. The puppet regime will require significant financial injections. At the same time, it will certainly be inefficient and corrupt. Given the damage from sanctions, fueling the regime will further exacerbate the shortage of resources within Russia itself. Even complete control of the territory of Ukraine will not prevent the West from forming and arming Ukrainian formations in adjacent territories, financing and providing for a wide underground in Ukraine itself. The war will lead to economic decline in the occupied territories, which will make their population even more susceptible to Western propaganda. If part of the territory is retained by the pro-Western regime, the conflict becomes permanent and protracted.
These scenarios are very well thought out, but a bit too high minded and think-tankey to me, if that makes sense. I think Putin's goals are more simple:
Russia has a puny economy, which is kept puny by kleptocrats.
If you want an example of how they operate,
look at Pavel Durov, who is Russia's version of Zuckerberg. He's not actually an oligarch, so they strong armed him into giving up his first company. Then he became paranoid, started running his companies like globe trotting cults, tried to start telegram as a crypto company, but pivoted away from that when the Western bankers explained they weren't going to play ball with him, so he and ended up running the telegram we know now, and he does it from the UAE.
The story of Pavel Durov is only one example. In the end, all Russian ventures end in either bankruptcy, or with kleptocratic oligarchs kicking in the door and forcing owners to sign away their companies at gun point, or because they are tortured. The point is, the Russian economy can not grow like this. At the same time, Putin can not remove the kleptocrats without destroying his own power base. This is a problem, because as time goes by, the Russian population grows, and infrastructure crumbles, and the state becomes more expensive to maintain, and it all falls apart if they can't get some economic growth, from somewhere.
So the only way for the Russian economy to grow under Putin is through conquest. They lack the resources for literal annexation of new lands, but they can set up puppet governments, in places like Kazakhstan and Belarus. In these vassal territories, the kleptocrats are free to steal from entrepreneurs all day long, with no consequences.
Ukraine recently got more energy wealth, from oil and fracking. Zelensky and his people would not let the kleptocrats simply take it, but a puppet like Lukaschenko would. So what Putin and his kleptocrats want, is to install a puppet like Lukaschenko, and then march out of Ukraine. (I know that sounds insane to the American ear, because we never march out of anywhere, but that's what normal countries do after a war)
They do not want to literally annex Ukraine, because they don't actually have the manpower or equipment to do that. Western media likes to imagine the red army is massive, and can annex everything East of Berlin, but that's just propaganda and cold war memories. Russia is puny now, compared to what they used to be.
In short: These are not high minded geopolitical geniuses playing 3D chess. They are simple gangsters who want to steal with impunity.
