Well, they could always do something like what EQ did and let any race go through a process to “betray” their faction and join the other, with a long arduous grind and/or time gate if they want to go back.
I honestly thought they were setting something like that up with Pandaren but it just never materialized.
I am all for the factions staying in place, but it would be cool if we could evolve to the point where it could be about more than race.
Factions of PRINCIPLES are interesting. Factions of race I feel are outmoded and boring, plus it kinda sends a bad message as far as what is worth fighting over.
I don’t think that alone would be enough to fix the imbalance. It’s just something that would be cool. But between that and some racial tweaks, and maybe some further pairing down of servers, it could be a start.