Is not yet in the game but will make its way to PTR where the testers will be able to trial the changes before they are implemented on live servers and the testing will last for a few weeks although Blizzard didn't specify the exact time period.
While that approach partially solved the issue the last time around, the devs are looking for a consistent way to give the players rewards. Following the players crowding out the Great Vault, Blizzard decided to give them the incentive to revisit the loot from Mythic Keystone runs but also avoid random upgrade systems such as Warforging. Mythic Keystone gear will be introduced which will return the Valor points. Naturally, feedback followed and Blizzard heeded the players as they are preparing to roll out an update that should give them more reasons to jump into Mythics.
Mythic Dungeons were fun for a while for WoW: Shadowlands players but they quickly ran out of things to farm in them which led to disillusionment and lower player counts in these activities.