Immigration will still play in AZ and TX and with white nationalist trenders, but in most of the rest of the country, everyone is going to work at someplace that has a help wanted sign out. It's a lot easier to get Americans worked up about immigration when there is high unemployment or at least fear of it. When Trump ran his 1st campaign, unemployment had fallen, but the memory of high unemployment was fresh and wages were seriously depressed. It may still be the GOP's best issue, but it's not going the get the traction it did 8 years ago, esp with any voter aware enough to know that Trump personally killed a reform bill.