At what point do some of the saner Senators see the picture?
The assumption here is that there are sane Senators. Actually they are mostly whores selling themselves to the highest bidders. That lack of morals will lead eventually to insanity.
Maybe sooner than you think. They can see the writing on the wall with Trump's surge, they know the base is very unhappy with the leadership of the GOP, they just haven't had any recourse until now.
Now you have Cruz openly defying the leadership. And I suspect, Cruz behind the scenes is recruiting others to revolt against the leadership, and either force them out, or bolt and start a new party.