I would not count on Russia balancing the costs of invading Ukraine against the gains and concluding invasion makes no sense. The ledger is broader than just Ukraine. China has to be considered.
A Russia-Ukraine open fighting or a Russian invasion of Ukraine is "relatively unlikely:"
But despite this intensification in regional tensions, the risk of a military confrontation between the two countries or an outright Russian invasion of Ukraine currently remain relatively unlikely. There are several reasons for this.
Well, our intelligence agencies said that it was unlikely that Russia would invade Ukraine in 2014.
But Russia did invade. The Economist goes over the history from 2014:
I quibble with the notion bolstered by the map that "separatists" control portions of the east. Russian forces were key to wresting that territory from Ukraine and Russian support is vital to keep Ukraine from retaking it. Raise your hand if you think that small impoverished entity could have more tanks than Germany, Britain, and France field combined, as I noted in this post.
I was extremely worried about the fate of Ukraine months before the invasion. Worried enough to look at a Russian invasion scenario.
One thing that I believe pushes Russia to solve their problem with Ukraine now is the five-year ceasefire Russia has with China. If Russia wants to pivot to face China by the end of that safe period, it needs time to mend fences with NATO.
Why Russia needs to pivot to China, if you wonder.
So unless Russia is resigned to vassal status under China, taking control of more of the Donbas and the Sea of Azov coast (and Odessa?) needs to be done now or not at all. Five years will let the West get over that "old news" of more Russian conquests of Ukrainian territory.
UPDATE: Hmmm. Is it really true Russia has 150,000 massed on Ukraine's border? That's about 50,000 more good quality army and airborne troops than Russia has, I think. Is this all service forces? How is this defined? Does this represent an increase in past estimates or just a different way of counting?