Exactly, Trump is useful, so let’s use him while he is still useful. If he destroys the GOPe, that’s a good thing, then we’ll deal with Trump.
The most useful thing Trump accomplished was to show just how serious the conservative grassroots are about securing the border and opposing amnesty. The message to GOPe is "run pro-amnesty candidates, and we'll either vote third party or not vote at all."
As I said before, it's an important message, if only we had a better messenger (i.e. one who wasn't saying the exact opposite 4 years ago when that's what it took to stir the pot and get in the headlines).