You had better fervently pray that those mass deportations do not happen. Forty percent of the people working in the US agriculture sector are undocumented. People will need to eat while this mess gets sorted out.
It will take many months, and more probably years, to replace the deported people with people able and willing to do those jobs. Some of those jobs are not low-skilled jobs either. In the meantime people have to eat. What will they eat?
Who are we even kidding here? Best guesses are there around 13 million undocumented people in the country. But the error bars on that number are pretty large. If you make generously optimistic assumptions we can have all state and local law enforcement, all of federal law enforcement, and all of the military (including reserves and national guard) that would be suitable for that kind of work assigned to do nothing but mass deportations. That would be something under 2 million people. Probably under 1 million in practice.
That isn't even enough to guard 13 million people in a prison. It isn't remotely enough to arrest and deport that many people.
Keep in mind that those people we'd have doing the deporting have other jobs. And those jobs wouldn't be getting done while this stupidity is going on.