Play multiple of the same class & just stick with whichever was luckiest in heroic week, or just play multiple toons as normal knowing that some classes will be stronger than others on certain fights. You make it an account-wide lockout & people will just buy multiple accounts. Blizzard won't stop split-running no matter how hard they try.
Those same guilds that spend more time splitting will just spend more time progressing and, more often than not, win anyway against the guild that's playing less.
Point of master loot is to just make the entire process quicker for a guild that will continue to use a loot council, as the majority of mythic raiding guilds will probably look to do. If it's tradeable, you trade it to the RL, and they loot council it... I don't like that system compared to what we currently have, and that's before getting into swapping loot spec for DPS players to get extra gear chances.