>>> The average Republican voter, regardless of who that voter supports, will vote for the Republican nominee.
I disagree. Without base enthusiasm, there is no victory. And if a brokered candidate arises, you can guarantee there will be zero enthusiasm...zilch, nada. In addition, spurned supporters of the leaders (Trump and/or Cruz if he too is spurned) will not only lack enthusiasm, but I expect fully to boycott, or worse. And as a number have noted, the losses will flow down ticket, as well. I would expect the Republicans to lose the Senate in that event, and come close to losing the House.
The base is much more than FR. The base will vote against the Wicked Witch even if it's for a Republican who is not who the base did not want to be the nominee. The Wicked Witch must be stopped. If the nominee is not Trump or Cruz, the base should leave the party. Trump supporters will join the new party that will be started by Trump.