Russia will go nuts, about as effectively as they have previously, and will likely fire indiscriminately into civilian population centers in Ukraine. Hope everyone has their cellars stocked, and their hard hats. Attacking civilian centers doesn't change the basic situation, that Russia just lost Crimea as it stands. Ukraine didn't even need to take out the canal, which is good.
Yes, Russia can go feral, and cause more loss of status, or they can cogitate their position, and politely leave Ukrainian pre 2014 territory, or they can try to escalate by going silly. They do not have an existential threat to Russia that doesn't come from their own destruction of the Russian military, that will come back to be a problem with their other states unless they protect and conserve what is left of their forces. Going "whole hog" apart from being a bad idea for the planet, will bring forward the collapse of Russia faster than anything else. Right now, if I was an advisor, I would be texting in to Vlad, rather than visiting him on the 6th floor with the panoramic windows. The advice would be the same, leave Ukraine under a cease fire, protect the forces you have, and cobble together the states that make up the federation. Vlad has a bit of kiss n' cuddling to do there, he used up a lot of good will by using the minority states as cannon fodder. That is coming back to bite him if he continues to squander his forces on his ill considered vacation in Ukraine.
Golly!
This may not have been missiles, it could easily be charges on the bridge.