I expect the Never Trumpers to keep trying, all the way to the Election. They would rather have Hillary than take the chance that Trump exposes their corruption. They have plenty of support thanks to idiots such as Glenn Beck, who backed Cruz with about everything he had (Cruz was the answer to Mormon prophecy, blah,blah,blah)
The most fanatic among them probably will try something else, write-ins or trying to put a candidate on the ballot in a few key states. I doubt they'll win any new converts to their self-destructive cause. It's mostly a question of how many hard core NeverTrumpers there are now.