With the late entry of Evan McMullin into the presidential race, an interesting metric will be the number of state ballots he will be able to get on.
I think this is a perfect for a bracketed market:
"How many State Ballots (including the District of Columbia) will Evan McMullin be on for president?"
1-5, 6-10, 11-15, 16-20, 21-25, More than 25
This cutoff at 25 is suggested due to fact that the deadlines for over half the states have passed, two thirds within a week, and the McMullin campaign will have to resort to lawsuits to get on the ballot, a very steep climb.