It doesn’t seem quite clear that winnowing the field will necessarily spell doom for Trump’s insurgent candidacy. If Kasich and Carson dropped out, there’s a good chance that at least a some of their support would go to Trump; Kasich polls well with self-identified “moderates,” a group favorable to Trump, and many of Carson’s supporters back him because, like Trump, he stands outside the standard political system. Some of Rubio’s supporters might back Trump if he dropped out, and, since Cruz has also made much of outsider themes, it is likely that a portion of his supporters could go to Trump if the Texas senator exited the race.

National primary polls are not always the best indicator, but, as the field has been winnowed over the past six months, Trump’s “ceiling” in national polls has gradually ascended. It’s possible he will top out at the mid 30s, but there’s no guarantee of that. He has won two out of the last three primaries, both by commanding margins. So far, Trump’s support has reached throughout many sectors of the Republican coalition. A recent YouGov poll found that Trump would win a three-way race with Cruz and Rubio comfortably. The idea that Trump will collapse on his own has so far proven to be mistaken. Moreover, even if a cascade of party elders does defeat Trump in the primaries (itself a debatable proposition), an establishment bandwagon will not necessarily keep Trump from going third-party and taking a substantial chunk of voters with him.