Before modification by Joel at 10/08/2015 01:14:08 PM
Sure, but many of them may still reconsider when the actual primary comes around, and they realize deep down that Trump as Republican nominee almost automatically hands the White House to Hillary Clinton. And Trump's disapproval rates are stratospheric - he may have fanatic followers, but most of those who don't follow him now are very unlikely to ever do so. Not like Rubio, Walker, even Bush, who can still convince lots of voters that they're the best candidate.
It is a truism that people giving him high poll numbers are distinct from those giving him high disapproval numbers, but the size of both numbers is due to the two groups combined constituting most of the GOP, hence neither can crush, or at least silence, the other. I do not know if you saw them, but some recent polls asking for a SECOND choice had Trump >50%: Not only does he have many loyalists, but many people who prefer other candidates say (FWIW) they would switch to him if their guy quit.
Maybe. I'm still really not sure to which extent Clinton's issues are genuinely serious. As thoroughly familiar as she is by now to everyone - for better or for worse - it remains puzzling how her approval ratings can swing up and down that much.
They are serious enough they could elect JEB by default: OBAMA administration inspectors general have asked the DoJ for two separate criminal investigations, and Obamas FBI is interviewing her servers company and her lawyer (who has many of the emails on a thumb drive) about the datas security. One columnist recently reminded us Sandy Berger received a felony indictment simply for removing classified documents as NS Advisor and failing to return them after he left; Hillary has done that dozens, if not hundreds, of times over. Then again, Berger was indicted by the same Bush administration that refused to indict Rove for leaking an undercover CIA agents name to Bob Novak, and even threw Scooter Libby to the wolves (then pardoned him) to avoid doing so. But Obama giving out midnight Ford pardons would do Hillary no good.
The worst case scenario for Dems is probably that the DoJ opens one or more investigations, but the laborious nature of such cases (compounded by the mountain of documents this one involves) delays its resolution until, say... just under a year from now? All the primaries are over, their delegates chosen, and Dems go to their nominating convention to annoint Hillary--and the next day she receives a dozen felony indictments. An even worse (but less likely) scenario is that an expedited investigation and trial bring a conviction by next May, which would probably cause the first brokered convention in living memory.
You misunderstand - I meant if, and I really doubt this will happen, Trump has already won the Republican nomination. With a choice between Trump and Clinton, there would be millions and millions of voters who might be interested in a centrist third party candidate, be it Bloomberg or perhaps even an actual Republican running as independent, Murkowski style.
Hillary IS the centrist candidate; she is just backtracking on all her positions during the last two "Democratic" presidencies to convince the left she has changed: Really! 
What distinguishes Bloomberg from Clinton? Tax cuts?