He will seek a different opening. Passing birdies keep telling me that's Balkans.
Balkans also have a little of value for Russia in the current state. A more interesting target would be to take control over Georgia or Azerbaijan (not necessary using military means), to establish a better control over oil and gas routes from the Middle Asia.
But a more realistic, much more valuable and easier target is the south-east Ukraine. If degradation of the Ukrainian state institutions continues with the current speed and the ongoing cold civil war will not be cooled down by a more sensible cultural and language policies, I will not be surprised to see in 5-15 years a full collapse of the state, significant social and economic instability, with breakaway regions following the Yugoslavia scenario, some of which will fall under the Russian "protectorate" for gradual later integration. We already can see early signs of it in the results of municipal polls, weak central government, and totally unprofessional behavior of the "elites" (who in the *#!? right mind spends most of money from the COVID fund on road construction and other non-medical goals?! who launches a full-blown constitutional crisis using clearly unconstitutional means instead of slightly tweaking the law in question or trying to engineer a constitutional reform to restart the corrupted constitutional court? who pays a ton of money to "anti-corruption" departments which after working several years haven't return a dime to the budget? who effectively strangles small businesses when they are already hit by the pandemic? etc. and etc.).
But Putin's plan appears to be to destabilise the EU from within by promoting extremist far-right governments with more or less obvious Russian influence and anti-EU sentiments.
See also Brexit, Poland, Hungary, and the Ukraine, and the - so far - less effective far right movements being promoted in France, Italy, Portugal, and so on.
This is much cheaper and more effective than sending in the tanks. You can promote regime change with a few social media troll factories and by buying or otherwise persuading local politicians.
It's not a coincidence that the threat of a hypothetical EU army was one of the main pro-Brexit talking points sold to British racists, or that significant funding for Brexit came from Russia.
As for goals - for Russia it's partly about revenge, and partly about the destruction of Western liberal values. Putin has said as much in public on a number of occasions.
The almighty Russian meddling can only tip public opinion a bit in the desired direction, but can not create it from nothing.
To not repeat myself, I will simply link my old comment: https://news.ycombinator.com/item?id=23743786
https://en.wikipedia.org/wiki/Foreign_involvement_in_the_Syr...
I highly doubt it. Baltic states are part of NATO, assuming Russia blitzkriegs them (it's a really HUGE assumption since they have relatively little geopolitical or economical value for Russia, the Suwalki corridor would be nice to have, but not considering the associated risks), leaving occupation unanswered will mean that US leadership position in the world (together with NATO) will be effectively dead. So further escalation will be practically imminent.
I think China's invasion of Taiwan will not be left unanswered as well, in addition to the huge reputation hit similar to the scenario with Baltic states, Taiwan has a big geopolitical (cornerstone of the first island chain) and economical value (not only TSMC) for the US. Further escalation is highly probable as well. A contained clash could've happened in the South China sea, but since China got entrenched there, the US Navy got quite careful to not overstep itself in this region. And this balance will continue to tilt only further to China's favor.
A limited conflict could in theory happen with a limited invasion of Russia, since its current nuclear doctrine is quite defensive (esp. compared to the US'), but the "threatens the existence of the state" condition is a bit vague, so assuming that Russia will use all its available military to defend itself, it will either drive invading forces out using conventional means (which would include counter-attacks on "decision centers"), or in the end will use nuclear weapons.