I think Adams is right that Trump has played the media exceedingly well and he has clearly surprised a lot of people. Some Republican pollsters have focus-grouped Trump supporters and found an extreme level of antipathy among them toward "establishment" Republicans. So it is unlikely his current supporters will abandon him in a sudden collapse, which is the failure mode a lot of Trump-skeptics have been describing. That means Trump will likely stay in the race for a long time--unless he gets bored and drops out. I doubt Trump will actually drop out though, he seems to enjoy the fray and clearly hates many establishment conservatives enough to stay in just to have a platform to keep attacking them.

Most likely Trump will split the anti-establishment vote with Ben Carson and eventually most of the establishment candidates will drop out and throw their support to an establishment survivor, who will manage to beat Trump with solid but not huge majorities and take the nomination. If Trump does manage to win the nomination, it is unlikely he will win the white house--odds are less than even, maybe 2:1 against him. Overall I would estimate a ~10% chance Trump wins the presidency.