The oil producing countries are always on the hit list of USA and this is happening in Russia as well. But Russia is not Iran or Iraq they have strong defence and they will not step back.
You think that Russia is any better in that regard? They would do the same thing USA is doing all around the world if they were capable of doing it. But since they aren't, they have to satisfy with conquering bunch of smaller neighbouring countries. Or you think that they became the biggest country in the world by coincidence?
No one can replace gas and oil from Russia, and we must be prepared for this.
While I am against sanctions as they are completely useless, Europe will eventually figure things out and find the replacement. It won't of course happen over night but it will in a couple of years. If this drags on (and it probably will), life standard in Europe will go somewhat go down, while Russia will crumble like USSR did since they learned nothing from that failed experiment.