Its going to come quicker than that...
Post Labor Day Congress finally decides to reconvene for their one month a year of productivity, and that's going to be chock full of fiscal cliffs and debt default deadlines. This will last until Oct-Nov and who benefits from that? 1) Trump, who will call all of Congress idiots and have near unanimous agreement out of the voting public as the spectacle rages on, and 2) Cruz, who will be the one causing the shutdown.
That crowds out Jebbers! who some people hilariously thought benefited from Trump's rise (

) even though he's now in 4th place, but also Media Flavor Of the Month Kasich, Walker, and all other governors who have nothing to do with it, as well as Senate lightweights Paul, Graham and Rubio who will have to light themselves on fire to get any attention during all of this.
Once we get to November, now the Iowa caucus is only 12 weeks away and nobody is paying attention from Thanksgiving to Christmas. As Trump is going to benefit from Congressional dysfunction there's not a lot of time to knock him off his perch as the clear #1 and its going to cost precious money since nobody draws free coverage like The Donald.
Walker absolutely has to win Iowa or there's no reason for his candidacy. He sure as hell isn't winning the SEC primary. Bush has to win in New Hampshire with its taxphobic but live and let live on social issues base. If he can't do that then he's useless as a candidate (same with Kasich who needs a strong showing). These are the very people who will get crowded out of the conversation come winter time.