There is an assumption among the hacks of the mainstream press and their pseudo-scientific sycophants that the presidency is Hillary Clinton's to lose.
Certainly she has the edge in the Democrat primary, however these bald statements ignore several serious obstacles to her succession to the imperial throne.
1. The Third Term Problem: It is a natural progression in democracies for the electorate to tire of the same faces and policies and seek to make a change. After eight years of increasingly autocratic Democrat rule, many who otherwise might be sympathetic to the Dems are looking for someone new and different. Hillary is about as establishment as one can be and there is absolutely nothing new about her.
2. The Classified Email Problem: Wags insist this scandal is empty but it isn't over and it isn't going away. The problem for Hillary is that documents aren't classified, information in them is. By insisting she never sent anything marked, she opens herself up to the charge that she is too clueless to know what a national security secret even looks like, let alone protect it. This is something a eunuch like Jeb Bush won't bring up but Ted Cruz will.
3. The Obama Coalition is Collapsing: The problem with hauling in 95 percent of any ethnic vote is that you can only go down from there. Put simply, the Democrat Coalition of the Aggrieved is turning on itself - Asians are realizing that they are now "white" and therefore evil and complicit wiht slavery, even though they had nothing to do with it. The very category of Hispanic is becoming so broad as to be meaningless - Mexicans have nothing in common with Cubans and no one has yet explained why people who came here 30 years ago want to see their kids compete against the latest arrivals.
4. Gun Control is a Losing Issue: Despite hammering it at every opportunity, even before the corpses are cold, the policy has never been less popular. As crime rises (thanks to de-policing and 'lone wolf terrorisim'), suppport for this this policy will erode further. Hillary's ill-advised temporary embrace of confiscation will ensure that her chances of carrying Obama states like Indiana and North Carolina is zero. She's also endangering Virginia, Michigan and Ohio.
5. Events: The world situation is deteriorating at an alarming rate, and her great selling point is diplomacy. This makes her answerable to every failure. As Russian influence expands and their challenges grow, that nonsense with "Reset Button" is going to haunt her.
6. Things Suck Right Now: The economy is pathetic, our military is weak and demoralized and young people have no job prospects. I've noted before that we likely have never left the recession but that the archaic and increasingly detatched-from-reality GDP measures simply won't record it. Normally an incumbent party seeking additional power runs on a platform of telling everyone how great things are. Not this year. To hear the Dems tell it, our colleges are overrun with rape, our economy is a shambles, crime is surging and none of it is their fault. This is not a good argument to make for continued power.
7. The Wrath of Obama: But simply, he doesn't want her to win on a platform of telling everyone that Obama's term has been a mess. He will end up undermining her at a point when it will do the most damage and leave the smallest paper trail back to him. I'm not yet sure if there will be an indictment of one of her staffers or a pre-emptive pardon after investigators threaten to resign in protest at the gross violation of federal law. Either way, the most petulant chief executive in my lifetime will exact some payback for her frequent campaign references about how awful things are.
If you have other reasons, feel free to add them in the comments.