Matthew Continetti has a piece at the Washington Free Beacon throwing some cold water on the chatter about a brokered Republican convention somehow preventing the nomination of Donald Trump:
I can see how maybe, just maybe, Cruz could win enough of the Trump forces and enough of the party regulars scared by Trump to win the nomination at the convention. But I can't see Rubio doing that, or Mitt Romney, or Paul Ryan. The delegates would revolt. The anti-establishment folks would walk out. If there is one thing the primaries have taught us so far, it is that there are more Republicans who back Trump and Cruz than Marco Rubio. Donald Trump has won the most states, set the terms of the political debate, and is in part responsible for record interest and turnout in the 2016 Republican primary. The idea that his voters would stand idly by—that he would stand idly by—as the convention nominates Rubio or Romney in his place is more than farcical. It's delusional.
Three things can happen. One of the other candidates can beat Trump. The party can fall in line behind Trump. Or the Republican voters who reject Trump can stay at home or vote for Hillary. Of the three, I think the likeliest outcome is the last one.