As of today, the following is my take on the candidates:
A) HRC: She is in real trouble. The reason is she cannot lie. Her handling of the email problem has been more than worse: it could kill her candidacy. Why? Because two important things people look for in a President: 1) Can the candidate understand me and do I understand the candidate?
2) Why does the candidate want the job?
In both of these she fails on the email problem. First, everyone who works understands the idea of having a 'work' email and 'home' email. The fact that she did not want to be 'bothered' by two emails, shows an elitism that separates her from the 'average Jane' (or Joe). She is just not like an 'average' person, but is 'above' all that. That is one way to kill a presidential campaign. Second, her lies were so obvious to be insulting. You are an idiot and I can lie straight to your face and you don't know it.
People don't expect a candidate to tell the truth 100% of the time. But if they do lie, they at least want them to be good at it. She fails on all accounts.
A second major problem is "the vision thing". Recall Pres. Bush (the first one) had a 'vision problem'. He had no idea why he was going to be President. HRC has "to be the first woman", but that's it.
Yes she has a ton of position papers, but why does she want to be President?
Result: Even with insane advantages, she may not get the Dem Nomination. (50-50) Even lower chance of beating a Reb.
B) Trump: 1) Everyone has seen Trump enough and has some idea of who he is. They understand what he is selling. The point is many are tried of 'weak' candidates and want someone to go to Washington and say: "Your Fired". The idea of a strong willed candidate appeals to a wide range of people. Thus, Trump's support is not ideological, but practical. With a few issues he has suggested he understands the basic person's situation.
2) Why? "Make America Great Again" The slogan is BY FAR the best of any candidate. He knows how to read the public and make a strong selling point. This is not to be underestimated because most of the other candidates have no idea how to do this.
The Reb nomination is currently his to loose. 25%
C) Bern: 1) Is not known enough by the general public, but a firebrand always has a place in American Politics. People can understand it and he does have many advantages.
2) A theme is both harder and easier for a firebrand.
Result: 35% chance of Dem. Nomination
D) Carson: 1) Like Bern a firebrand. 2) A theme really needs to be voiced that is more concise than his current talk. He needs a Trump advisor to get a witty slogan.
Result: 35%
E) Biden: 1) Son. that's a huge story and one that can propel him to a win
2) Much harder but if he can get a good one line reason: could be a winner.
Result: If he runs 50%, but 50-50 he runs
F) Reb Field:
It's really hard to figure the candidates out this far out and this many. I suspect one will make a stab at the two front-runers.
Result: 45% chance an 'established' candidate gets it.
If forced to pick today (this may change), I would guess a Biden-Carson race, but this has a low probability of happening.