They could set up an overall PvP faction-based rank and title system where Alliance PvPers are addressed as Knight and Horde PvPers are addressed as Champion. Then we could take it further and set it up like this:

Bronze Ranked Knight/Champion
Silver Ranked Knight/Champion
Gold Ranked Knight/Champion
Platinum Ranked Knight/Champion
Diamond Ranked Knight/Champion
Master Rank Knight/Champion
Grandmaster Rank Knight/Champion

Each rank could require accomplishments from several forms of PvP, so it isn't just tied to one thing. Bronze rank could require winning 10 arenas, 5 rbgs, 20 random bgs, and getting 1000 honorable kills or something. Diamond rank could require 2200 in 2s, 3s, and RBGs, as well as opening up old achievements again like The Flaweless Victor, and requiring their completion (win 10 straight matched in Arena). Instead of the lame prestige system that is just based on grinding and nothing else, this would replace the symbols hanging on your unit frame with something similar.

I mostly just want to see new ranks and titles that are genuinely cool, and I think having a system that encourages playing all forms of PvP would make PvP flourish more overall, rather than segregating parts of the PvP playerbase. Bring people together and let them appreciate forms of PvP they may not have tried or taken seriously yet.