In New York after a trip to Europe, Richard M. Nixon last week had a word or two about November for newsmen. “The gubernatorial contests are the real sleepers as far as Republicans are concerned,” he said, and went on to predict G.O.P. victories in New York, California, Pennsylvania, Ohio and Michigan. As of now a sure win seems certain only in New York, where Democrats have not even found a candidate to face popular Nelson Rockefeller. Good G.O.P. possibilities: Ohio and Pennsylvania. Tossups: Michigan and Nixon’s own California. But Nixon’s prediction, however sanguine, threw sudden light on an interesting fact: the Democrats are not shoo-ins in the five states with the biggest urban vote.