Can't say for certain how they would react to repeated Trump losses, but if they behave anything like the Newt supporters did on FR during the last election cycle (and Newt was definitely 2012's version of "Trump" on this forum, his supporters dominated FR and shouted down everyone else), then they will NEVER concede he's "through" regardless of how many times he loses.
In Newt's case, he had only won two states nationally out of two dozen contests, including losing everywhere but his home state on Super Tuesday. The fact he now had zero chance of being the nominee didn't damper his fans enthusiasm one bit, they will still chanting "all the way to Tampa", talking delusional prospects of a "brokered convention" and still fantasizing about a "Newt/Herman Cain" ticket long after he had ceased to be a contender and frequently ended up coming in 4th place.
In the case of Trump supporters, we can only judge their reaction to Iowa thus far, where overnight it went from lofty predictions that Trump would win every state and "run the table" and that "Ted Cruz peaked too early there and his support has now tanked", to talk of how Iowa "doesn't matter", "never chooses the nominee", and how "they're a bunch of so-cons who vote for which candidate says he loves Jesus the most"