On the Republican side, who knows? Trump can't fully unite the party if he wins the nomination, and it's possible he'll prevent unity if he loses. And it isn't clear that Cruz could unite the rest of the party if he's the winner, even without Trump throwing bombs from the sidelines. But expect at least some boost for the eventual nominee anyway. The incentives to unite are strong. There's no way to know what the Republican Party will look like after its convention in Cleveland.