I like the idea in general. As you have it I don't think it'd work for the devs or as @Tigzie said, would potentially knock some peoples back.
I would like to see a prestige system where, at a max level, you can specialize a toon.
So like, now, with max gear/7star/lvl 85 - you could choose to make her Master Lumi (more fighting, new combat ability) or Forcehealer Lumi (better healing, new defense ability).
Like the end of the Clone wars show - Baris should have an option to stay lightside and maybe repair protection or go darkside, and get two lightsabers and attack better
5's can stay stalwart, and get some addeded defense or you can go prestige Insane 5's (when he gets his chip removed) maybe he deals damage to everyone (like 5% to his own team) but gets more attack.
Assajj go prestige into Night sister mistress (staying how she is, but more numbers) - sith apprentice (gains the sith type, gains a force move) - or Bounty Hunter Assajj (gets the bounty hunter type too, gets a stealth ability like othe rnight sisters or something)
I'd like to see more ways for the current toons to differentiate, so you can call them 'yours'