Hear me out: With M+ gearing now in the mix we no longer need 3 raid tiers (4 if you include LFR) and having 3 tiers fractures the raiding player base too much. It’s gotten to the point that filling both normal and heroic groups is difficult. Players will start normal and then once they “m+” past that stop showing up. Raiding populations should look like a pyramid with the largest number of players showing up for normal, second largest for heroic and smallest in Mythic. But that is not the case anymore.
Instead of 3 raiding tiers, just reduce raiding to 2 tiers and use systems like valor to bump your normal raid gear along with m+ until you can do mythic.
Another plus is that developers can spend more time on something else instead of an unnecessary third raiding level.