All gear has a rating, perhaps a char's average rating as a cutoff for brackets?
No swapping once it pops then. And assuming there are sufficient bodies to populate both queues.
The issue is not brackets, the issue is WH gear is not accessible enough. The PVP is actually great in this game, and people want to play and be competitive. The trouble is, at the moment they can't. It's probably the largest contributing factor as to why so many people have quit. The lengthy grind to WH whilst getting your butt handed to you over and over and over is just terrible. It's actually the worst grind for PvP gear I've ever experienced in an MMO, it really is no wonder why so many people have quit.