Russia would not be able to completely rebuild what it had; for instance, i do not believe they would be able to retake Baltic states or the more central European territories unless a total collapse of the power structures uniting central Europe occurs. They aren't in a position to really invade or occupy, as they have already been launching campaigns in more distant regions (Crimea, Chechnya) which have been quite the struggle. I see territorial gains for Russia, if they were to come, being the "prize" for choosing the right side in a major conflict.
For anyone interested in Russia's moves, and how the past is literally writing the present day policies, check out these posts I made about a year ago. Russia's present situation and how it relates to their longterm goals, whether they would side with China, and a lot of geography broken down here with some pretty pictures as a visual aid.
On land, resources,, etc:
https://kiwifarms.net/threads/merke...us-no-longer-a-world-power.72296/post-6803925
On russia's military moves, the expansionist role it has carved out,, and why it is doing this:
https://kiwifarms.net/threads/south-china-sea-and-chinese-military-developments.68791/post-6995964
On how Russia has the single corridor which leaves Beijing the most vulnerable. Aka: why the Chinese are likely to prioritize any alliance with Russia in order to secure this backdoor:
https://kiwifarms.net/threads/south-china-sea-and-chinese-military-developments.68791/post-6998859
On the fluidity of the position Russia finds itself in:
https://kiwifarms.net/threads/south-china-sea-and-chinese-military-developments.68791/post-6993528