Those primaries are a long way off, and I do think there’s a strong possibility Trump will self destruct. He does control a large part of the protest vote for the moment, but there are only so many protestors. You can imagine the moderate/centrists in blue states will rally to Jebbie just like they did for McCain and Romney.
I see this as the reverse of 2012. Then conservatives were split between a bunch of candidates each of whom self destructed in turn. This time that was supposed to be replayed with Jeb, but the dogs won’t eat it. Enter Trump, with unlimited money, name recognition, and the ability to get his message out without even spending it. Now the situation is reversed. It’s Trump way out in front early, and the GOPe desperately looking for someone to stop him. Trump may not get a majority, but he will get a plurality of votes and delegates, just as Romney did. If that happens, how can the GOPe deny him the nomination, especially with the threat to run third party? Not that he could win a third party run, the sore loser laws in key states would prevent that, but he would be a spoiler. The GOPe may have no choice but to nominate him.