AAAND.. he's filed his financial disclosure. 10 Billion Dollars!
The repubs thought he wouldn't. Are pants being soiled?
I don't think so. This primary may be quite like the last one. You have Jeb Bush, the "moderate" establishment candidate and a horde of crazies. There is a strong "anybody but the sane guy" element in the GOP and they flipped between heavily backing one candidate after another last time trying to find someone who, while crazy, was still electable and there was a new Not-Romney every month before they grudgingly agreed to go with Romney.
Trump may simply be the first in that list. His money might give him staying power or he might get old fast. At this point, the other crazies should feel comfortable just sitting back and waiting for people to get tired of his schtick and then try and get the nutters to back them for a couple of weeks before moving on to the next Not-Bush.