Probably true. There will be an initial rush of support for Thompson. Then the dynamics will shift again as voters are finally able to look at and hear Thompson on the same stage as the other candidates. Thompson will be a strong candidate, but he will probably not become the runaway favorite. Thompson might never be stronger than he will appear two weeks aftr his official entry into the race.
I like Thompson, but he's not without flaws. McCain-Feingold leads the list of fiascoes he was responsible for. Beyond that, he has almost NO executive experience. He has never led anything larger than his own personal senate staff. He looks a lot like Obama and Hillary in that respect.
Thompson will gather his support from the McCain/Tancredo/Hunter supporters, leaving a three-way race into the February primaries between Giuliani, Romney, and Thompson...should be interesting.