I recall that in 1960, Vice President Nixon was deemed a strong possibility for winning the presidency, by virtue of the fact he had no primary competition, what happened? A guy called John Kennedy who had been seasoned and steeled by a vigorous primary campaign, by virtue of the fact of him selecting Lyndon Johnson narrowly won that election. The lesson is this, Hillary might not have to endure a competitive primary campaign, that doesn't mean she has a lock on the election. For example say her opponent is one of the following individuals, Jeb Bush, Mitt Romney, John Kasich, Chris Christie or Rick Perry
https://www.youtube.com/watch?v=uWXRNySMW4s