There are still 15 candidates and four months before the first primary. It doesn’t matter whether he’s at 20% or 30% in the polls; what matters is that (1) Jeb Bush is in single digits and (2) he converts his 20-30% polling into a ground campaign in the early states. Watching the last few cycles, things change very quickly based on the results in Iowa, New Hampshire and South Carolina. Nothing makes things real like actual people showing up and pulling actual levers for their preferred choice.
You have that right about people showing up and pulling levers... in South Carolina, GOPe will be getting democrats to pull levers for Jeb so Trump needs to really focus on getting 4x the regular primary voter turn out to show up if he wants a chance...