Jeb is no shoe in. My list I just posted: http://www.freerepublic.com/focus/news/3259161/posts?page=44#44
The Democrats voters will know who their nominee is very early in the season, no matter how the voting is going, and many will vote in Republican open primaries or will change registration to vote in the closed primaries.
Conservatives could win by all the opposition candidaates to, say Cruz or Walker, dropping out right after or before Iowa. Then that candidate would have to be totally impervious to the nastiest campaign of falsehoods and general vilification that has ever been run and just soldier on. Having several conservative candidates gives voters someone else to turn to when the favorite is covered with the RNC scheiss and so disappears. With only one the vilification would be much less or not at at all effective barring a lapse into "explaining by the conservative." As soon as he defends against charges he effectively validates them and loses.