Problem 1: Ms Khan does not understand the ideological roots of Islamic extremism and, therefore, won't have the foggiest about how to counter it.
(But this will be true of anybody appointed to the role by government. Mind you, I think Maajid Nawaz fancies himself for the job.)
Problem 2: No Muslim "group" will co-operate in good faith with the Prevent strategy or any other like it, and most especially not the MCB, CAGE and MEND, all of which organisations are themselves extremist, just not violently so.