Writing in the New York Times, guest columnist Orlando Patterson (a Harvard sociologist) claims without much justification that Colin Powell "stood a good chance of winning the presidency on the Republican ticket had he run":
A black man has led the world’s most powerful military machine and stood a good chance of winning the presidency on the Republican ticket had he run; another is now a leading challenger for the Democratic nomination.
But what are the odds that Powell would have won the Republican nomination in 1996? He was pro-choice and pro-affirmative action, which are not exactly winning positions in the GOP primaries. Even if he had a good chance in the general election (which he probably didn't given the state of the economy at that time), the joint probability of him winning both the nomination and the general election was very low.