Likely pretty much the same, really. Sino-American relations, though they were strained as a result of Tiananmen Square for a time, were always fairly strong after detente. Sino-Russian, relations, on the other hand, have always been rather bitter, and border skirmishes between the two have happened even during their time of so-called alliance.
Really, it doesn't change anything essential. China still depends on the United States as an export market, China is still wary of Russia (though most certainly moreso), and will most certainly depend on the United States to act as a counter to potential Russian expansionism in East Asia.