The nominee has had the nomination sewn up by March the last two times around, by June of next year we’ll be looking at Jeb Bush as presumptive nominee if people wait until then to decide.
There’s no question that the GOP will nomínate Bush. That’s as certain as anything can be.
The questions are, how many major campaigns will there be (3,4, or 5) and can the political system manage and survive the chaos that will result?