Writing for RealClearPolitics, Michael Needham demonstrates the two strands of Republicanism with any significant votes behind them are conservatism and populism. Cruz represents the former, Trump the latter. The old GOP "establishment" of Bush and Rubio is an electoral non-starter in 2016.
Needham's point: the party needs both strands, meaning either Trump needs to be more convincingly conservative or Cruz more populist. One gets the sense he'd prefer Cruz but is willing to work with Trump if that is the voters' will. It's a sensible position, one I share.
Perhaps Trump is nominated but can't beat Clinton. Goldwater was once our choice and he failed against Johnson; disappointing, sure, but part of politics. McGovern was another such choice, on the other side ... it happens. Our ship of state has mostly withstood Obama's depredations, Clinton isn't likely to be significantly worse. And just maybe whoever we nominate wins election.