Since there is a thread talking about removing it from frost and fire I have an idea, keep all three trees their bloodlust, but each spec also gives extra buffs that linger when the lust is over.
Arcane
Time Warp, cool down reduction for the party or raids abilities by 20% for 30 secs when it wears off.
Fire
Blazing Fury, grants a 5% increase to the raid or party’s critical strike chance for 20 secs when it wears off.
Frost
Glacial Assault, grants the raid or party immunity from knockbacks and increased versatility by 5% for 10 secs when it wears off.
This keeps each tree their ust, but it makes each one unique and ideal for different situations, frost ideal for PvP, fire ideal for both PvP and PvE, Arcane for PvE.
Note that this will make Shaman or Hunter lust obsolete and weak compared to this. I am aware but this is just for fun, I’m not really expecting this to even be implemented