I have a fun idea for raids -- would be interesting if they released a raid tier where the bosses are not sequential and each boss could provide a small buff that would help against his opposite boss -- similar to how bosses work in the mega man series. Would be fun to have a little strategy involved with deciding on your desired kill order and it would be interesting if the buffs could help make up for holes in raid composition.
I'm sure ultimately players would discover an "ideal route" but it might be something fun to spice up the raiding environment. I guess this is similar to the deathwing fight when deciding on which platforms to fight on first, but maybe create some more interesting abilities that would specifically counter a boss' mechanic.