Except he wasn't. He warned about the problems of Islamic terrorism and open borders/illegal immigration in his 2000 book, The America We Deserve. That's a decade and a half ago (and pre-9/11), not just a few years ago. These two issues are fundamentally fueling his current campaign.
In addition, I'm pretty sure it was Ann Coulter (among others) who reminded people not too long ago of the full-page ad Trump took out in the New York Times in 1989 calling for New York State to reinstitute the death penalty. His current campaign is pro-police/law & order, which seems in keeping with his views since the Eighties. He has also been for decades now one of the few people who has a concealed-carry permit for New York City. Most lefties wouldn't pick up a gun to literally save their lives.
Of course, in interviews from the 1980s he used to really get worked up about how the US is being ripped off in its trade deals with other countries. I guess one could argue about where in the political spectrum that one falls, but a lot of people on the right feel the same way and it does show consistency.
Someone else wrote Death of the West in 2001