Clashes between Russia and China are not unheard of. See Sino-Soviet border conflict. Recently Russia ceded some territory to China as well. Lots of chinese are working&living in that general area, which is far closer to Beijing than to Moscow. Not to speak about difference in population amount.. Siberia 40m and sinking, China 1400m and raising.
The US needs a source of cheap products, G2 was suggested by the US, not China. China soon will have a typical dilemma, as it gets richer, so would like the workers, but as cheap labor is what makes China richer, its either one or another. Or landgrab. Now i dont think Chinese have the spirit to do that alone, but in alliance with USA they could. That too is not unheard of.
Europe.. its a total mess, already actually. One thing is sure, w/o US money all those "small independent democracies" aka puppet states immediately go broke and back under Russian influence. That or they go into a state of anarchy like its happening with Kyrgyzstan right now. Either way Russia will not face a 2 front war.
As for the Arab thread i think its overrated because they are not integrated into world's economy. USA invaded Iraq, Afghanistan. Israel invaded Libya or something. Nothing happened. Noone really cares, or does anything other then talk. At a slight sight of danger they are glassed and life goes on.
again this assumes that the world goes broke first, war second heh.
God, Chome's spellcheck is awful and i havent slept the night..