While Trump may be ideologically flexible, his electoral base is not; that base fervently believes in an impossibly expensive enterprise, the rounding up, legal processing and deportation of 11 million US residents, and the walling off of the border with Mexico.  Beyond the stupendous cost of such an operation, which would involve greatly expanding police and court resources for a period of years, our own economy would further suffer in a way we would feel from the loss of all that creative enterprise  among those residents, the taxes they pay, and the goods and services they consume.  It would be an economic disaster.

Trump may well be aware of all that, in which case he was luring bigots to his cause with a deliberate fantasy.  By suddenly turning off that inflammatory rhetoric, he has hung his followers out to dry, and many are outraged. What will he do now?  This may be the effective end of his campaign.