Of course Trump will lose, and it is in fact reflected in current polling. Head-to-heads have long shown Trump losing to everyone except Bush, who has long fallen into irrelevance anyway. Trump may very well win IA, and right now he looks like an overwhelming favorite to win NH. But eventually, the other candidates will coalesce around one person (right now, I suspect Cruz has the best shot by means of winning IA. But it may be that Trump will win IA/NH/SC and that an anti-Trump will only emerge later; it doesn't matter), and whoever that person is will smash Trump like the bug he is.
The problem with this analysis is that it's definitely not a given for any candidate to drop out early enough for support to coalesce around an anti-Trump, especially in the post-Citizens United era where superPACs can handle the heavy lifting with big ad buys.
As ironic as it is, Trump is in the same position that Romney held in 2012. There were quite a few candidates that would have defeated Romney in a head to head race at various points in the campaign, but the race was never just Romney vs. Anti-Romney (even as it got later in the primary season, Gingrich and Santorum were still acting as spoilers for each other) and this race will never be just Trump vs. one Anti-Trump.This race will never be Trump vs. one Anti-Trump, but it doesn't need to be. Romney won a string of very narrow victories over Santorum by utilizing his superior fundraising and ground game/support for the establishment, which is something Trump will be unable to do against anyone who emerges as the Anti-Trump. Also, I question that Gingrich and Santorum were acting as spoilers; after the February 7 primaries (Colorado/Minnesota/Missouri), Santorum emerged as
the challenger to Romney and Gingrich afterwards rarely hit double-digits outside the South (where Santorum largely won anyway). Of 16 Romney victories over the period between February 7 and Santorum's drop-out on April 10, Gingrich+Santorum>Romney was only true in four states (Wyoming, Michigan, Ohio, and Wisconsin). Also, while both were "anti-Romney", Santorum ran a strongly socially conservative campaign while Gingrich's was more fiscally conservative/personalist, and I don't know how many of Gingrich's voters would've sat out or had someone other than Santorum as a second choice. The point being: saying Gingrich spoiled the nomination for Santorum isn't really backed up by the data.
What you're saying about the superPACs is true, but this is not a field of lots of strong candidates with well-funded superPACs trampling on each other's toes: the field is overwhelmingly under 5%, both nationally and in the early states. Also, if someone begins to emerge as the Anti-Trump, the pressure to back off from donors, for an establishment politician (say, someone like Bush or Rubio; this may not apply to, say, Cruz, and certainly not to Carson) will be much greater than the pressure on Gingrich to step aside for Santorum ever was.
A Trump third-party candidacy is pretty much logistically impossible at this point, for the record, due to ballot access requirements, filing deadlines, and sore losers laws. I guess it would still be possible if he wanted to flush tens of millions of dollars into a nationwide operation dedicated entirely to just getting his name on the ballot every where, but the point of no return for even that option is rapidly approaching.I know this, but Trump's begun floating the possibility again and it's been brought up on other threads.
Also if he were to run as an independent I would not be surprised at all if Trump also got a bunch of his prominent supporters to run for Congress across the country as some sort of "MAKE AMERICA GREAT AGAIN PARTY" and it'd be comparatively easy to do if he already had ballot access operations funded in all fifty states anyway. This would maximize Trump's spoiler effect, as a "[Inks] you" to Republicans all across the board (just imagine Mike Ditka running against Kirk in Illinois, Hershel Walker challenging Isakson in Georgia, Hulk Hogan running in Florida, etc etc)
This I doubt, on the other hand. Trump's always been a solo act and tries to avoid fraternizing with other politicians (even if they would be "outsider"-like politicians). I don't think he would recruit others to run for down-ballot offices (certainly not for House seats), and if he did it would be an irregular patchwork, probably of Trumpian yes-men who would run far behind Trump. The Trump does not like to be upstaged.
"losing this election is good because it means we win the next one" is never a solid philosophy - a bird in the hand and all that
You're right, but I do think keeping control of Congress in this election for Republicans is more significant than winning the Presidency -- ultimately foreign policy is very much predicated on the individual holding the Presidency and the circumstances of the era as opposed to domestic politics, and the President takes a backseat to Congress on domestic policy. I
do think Trump running for President as an independent, unlikely though that scenario is, would help Republicans in congressional races, unless he deliberately recruited spoiler candidates (which seems out of character and a tactic of dubious success anyway).
