Trump wins either way.

Boneheaded is an understatement. On one hand, the charges could potentially be thrown out if the DA is disqualified and a Trump-friendly replacement gets to make the decision on a new prosecutor. On the other hand, whether or not anyone gets convicted on this doesn't really matter because Trump now gets to continue to bang the drum (with some evidence this time) on how the system is rigged against him and and he's being treated unfairly. Regardless of outcome, Trump and his supporters will extrapolate this one incident to try to argue that all charges against trump are rigged. While those arguments will be convincing for people already in Trump's camp and unconvincing for never-Trumpers, the real question is whether or not it will sway enough of the few still on the fence to have an impact on the election.