Okay, this is my take on it. You could call it a fantasy if you want. USA attacks Russia first by hitting the Russian base in Syria. What will Russia do in return? They will hit all the American bases with all their rockets. What happens to America? People of America will revolt. Mexicans in Los Angeles will attack the capital and capture it. And, all kinds of other groups in America will do the same through out entire America. America could be captured by their own people and have Russians come and take over the Washington. China will control California. Canada controls Michigan and all other states by their border. Florida is captured by Cuban people.
If we attacked Russia, we would attack about 300 places at once. But we might just unleash Thor's Hammer. We've had that for many years now. And it provides absolutely no warning. RADAR is useless.
Interesting theory, but I now don't think a US-Russia clash in Syria would lead to a wider war. We tested that a few months ago when a team of Russian mercs attacked a US occupied base and got creamed. We killed several hundred Russians and there was barely a peep from Putin.