This war is going to be a land grab war...
I doubt it will escalate to the point of nuclear catastrophe...
What will happen?
Russia will start gathering up all the countries around it slowly, through annexing... There will be no invasions unless that country has a terrorist organization in it...
This will be easy to do, since russia can self sustain with oil... It will need very fertile lands though, so that is why they need to annex countries like Ukrain, Turkey, Iran, China, etc...
Russia already convinced China to drop our currency within the next few years, so once that happens they will be a political powerhouse...
This won't destroy our economy, but it will through us into panic.
Once US population is panicking and nearly revolting against our govt. Russia will heighten their annexed countries with many defenses... Their plan will be to grab many of the middle east countries, and wait us out. (or starve us out if you will)
This will be the reverse of the first cold war... America will in return try to get Guam, Philipines, Indonesia, Japan, S. Korea, Thailand, Kuwait, Israel, etc. to arm up their forces and sign new articles or war... While this is happening, Europe will be on a complete scramble trying to fight Russia in legal battles to get Oil back into Europe...
The U.N. will file sanctions on Russia, and Russia will probably just laugh them off...
After this huge chess match this will be the result... America will be the new Venezuela... We will be a story of an inflated currency that bit off more than they can chew... Russia will have regained the former Soviet Union, and Europe will all be what Greece was in back in 2012...
It is as simple as that...