For America, watching from the inside, this is highly unlikely. The worst case scenario for what's going on right now would be something more akin to the Troubles in Ireland than a full-on civil war for any number of reasons.

A war with China will do massive damage to the European and world economies, though, even if Europe stays entirely out of it. China more or less stops exporting (and importing); the economies of South Korea and Japan immediately contract 25% or more; Russia faces massive and nearly infinite demand for its resources from China; oil states in the Middle East would face massive price volatility followed by a collapse in demand and a loss of 50% of their government revenues; and every two bit nation in the world would decide now is the time to pursue revanchist feuds since everyone who could object is otherwise occupied.