A handfull of attention seekers, no big deal.
It’s not a big deal at all since the few loons who actually carry through with their threat are more than offset by the many thousand Trump will attract from the Democrat Party and their many minority coalitions.
I wouldn't bet on it. Cruz got a huge chunk of the constitutional conservative vote, and those people are not happy about their man being wantonly trashed. Nor are they particularly happy about the gloating displayed by the winning faction ... especially since the proper time for gloating has yet to come.