The Ukraine disaster is about an easier, cheaper, and more secure (for Russia) transport corridor for heavy natural resource goods. Putin if he had more than two neurons to rub together should have stuck to the plan of undercutting Ukrainian governance in the eastern Ukrainian provinces, and then used the chaos to negotiate the corridor through the rest of Ukraine while leaving the actual pro-Ukraine part of Ukraine intact and without need to kill thousands of people with moronic moves.
Those two eastern provinces WERE rallying against central government and would probably truly "welcome their Russian friends as liberators" allowing Putin to install puppet governments in the two "new states." (note that Russia has already long recognized their "national status.") Why are those two "different"? I'm going to guess that this is the result of an old Soviet plan long before Putin. The Soviets took areas which looked potentially strategic and removed most of the native populace and replaced them with persons not native to the areas, including many Russians. Both Kazakhstan and Uzbekistan are prominantly structured this way (Samarkand being about 50% Russian citizens) and guess what?: that's where most of the natural resources are. Those eastern Ukrainian provinces were ripe for "revolution." But because Putin is either a powerful buffoon, or a not quite so powerful politician, he went full-stupid and decided to grab it all. Thus the sanctions as his reward.
Will these sanctions "destroy the Russian economy?" Well, no. They will constrict it temporarily and hurt the population, and even the oligarchs, but destroy it? No. Unless Russia was bombed back to the Stone Age, its economy will persist and grow over time. Why? Because it is a resources Giant. As long as the rest of the world keeps chasing technological growth as fast as can be possible (no one should doubt the global economy's intent there) the racers will desire Oil, Gas, liquid fuels, other oil products, coal even, Iron, Titanium, Aluminum, rare metals, fiber (a la lumber), and a lot of things that I no longer remember from studies done before I got old. ... and no, you can't just go to another "store" and buy them --- not at the speed and competition that the global economy demands.
So Russia's economy will rebound. Germany will still want {badly) the energy resources. Russia was on the path to a major upgrade in its economy unless something stupid happened. Putin happened. When he's gone, the Russian economy will join the Globe again.
