The #NeverTrump movement is toast.
Again, #NeverTrump is Republicans who refuse to vote for Trump in the general election. It isn't toast unless/until Trump is elected president.
It is toast when Trump becomes the nominee, the same way PUMA was toast when Obama became the nominee.
Unlike with the PUMAs, there are way too many high profile Republicans (both politicians and conservative media types) who've thrown in their lot with #NeverTrump for all of them to backtrack now. There is no going back.
For that matter, I think #NeverTrump will grow among Republicans in Congress after Trump is nominated. As of now, many of them have simply dodged the question as to whether they would endorse him if he's nominated. But once he is nominated, it's no longer a hypothetical. They'll have to choose.
There's a chance some Republican senators not up for reelection might speak out against him, but I'm skeptical that many congressmen will, unless they live in a district that was hostile to Trump in the primary. They wouldn't want to alienate his fans.