Miller's position in immigration is to
- have the most hardline stance
- to throw in monkey wrenches in possible deals (see 20 bil for DACA but then he decided to add 4 pillars and then started talking about amending the constitution to remove birthright citizenship)

Miller has killed a lot of deals, that's his job to cause chaos when things don't go his hardline way. He hasn't been fired yet and I don't think he will. Trump is betting big in 2020 that voters are against immigrants and removing Miller just doesn't make sense. If he's betting big on anti-immigration as a way to get re-elected, things will get worse.