... 'tis the "Trump support" bit that's worth noticing

Cruz Soars to Front of the Pack in Iowa Poll;
Trump Support Stays Flat

Cruz may, indeed, end up the nominee... but my take-away from the headline is "Trump Support Stays Flat".
The Donald has a VERY SOLID base of support... at around 30% of "likely GOP primary voters".
Even if we assume these "likely GOP primary voters" constitute every Republican or Republican-leaning voter, that's something like... hmm... 30% of 50% = 15% of the electorate.

Forget a brokered convention: I'm hoping for a clear Trump victory!
Let's pretend that of the remaining 70% of Republicans, 3/4 decide to vote for the party's nominee.
... that totals something like 41% of total popular vote... enough to lose.
In modern parlance, this would be a landside for the Democrats.
(AND: I'm not at all sure that even 3/4 of Republicans - other than those committed heart & soul to Trump - would bother to show up at the polls.)

Of course, I'm not Nate Silver.