Sadly I don’t think Ion and Co will ever lock dynamic flying behind Pathfinder, it’s their creation unlike TBC flying. Just look at the patch notes, they removed dynamic flying from Pathfinder for BfA and SL, yet left that requirement for TBC flying. It’s clear they have a disdain for TBC flying.
Actions speak louder than words and they are making it very clear they don’t want TBC flying to exist anymore, but know they can’t outright remove it, so they are going to put as many obstacles to getting it as possible.