But creating a hostile enough environment for sanctuary spots may send the illegals fleeing America, anyway.
No, they won't be fleeing. They aren't going anywhere until they're physically removed with a deportation order. There is no easy way to solve this, I wish there were, but there isn't. These people are criminals, they were mostly criminals of one type or another where they came from, they brought it with them, their crime organizations got them here and paid the smugglers to haul them in. They have jobs to do for these criminal cartels and enterprises, so they aren't leaving on their own. They never have, they never will. Some of the visa-overstays will leave on their own, but the ones who crossed the border, oh no, they'll never leave.