That's my view as well. He's performing a service, IMHO, because he's forcing the other Republican candidates to play a little less cautiously. It makes them more vulnerable to media ambush, to be sure, but they're going to have to deal with that at some point in any case and if Trump can deflect some of it, so much the better.
They really don't want to be distracted by him in this way, they'd prefer to wear down the other Republican candidates, but they can't help it, he's drawing them like moths to a flame. Whatever else, he knows how to generate buzz.
There is a very real anger on the right, (and I think in the silent middle as well) and it's building by the hour. If Trump is the only vessel for it, we've got a problem, but if the other candidates step forward in that role we've got a candidacy. I'm hoping for the best, because we've got to stop playing a cordial, nice-guy losing hand as McCain and Romney did.
Trump is making every man in the GOP field better.
They are forced to be and get better when they have to walk the gauntlet of PC, Trade and Immigration.
So far, he's the only man in the race.