Meta charms will never be a thing - otherwise Truine cycles become too overpowered. This would completely negate the effects of the charms downscaling.
Also I'm not sure that most people understood Marco's intention (or maybe it was I who misunderstood).
Marco wrote:1) Many builds have become non viable simply because they lack uberpower. The goal here is to simply make builds that are not that straight forward not get so punished when they first hit the end phase of the game.
2) Median XL isn't all about: What build can beat all ubers?
How I understand those lines: 1) Difficulty would be such that a larger variety of builds will be able to progress through destruction and complete a number X of ubers by playing correctly / having correct itemisation INSTEAD of needing the support of charms. AKA more emphasis on smooth progression and
gameplay (if you got the skill) rather than gearing/grinding/trading for charms.
2) The hardest of ubers will still remain difficult. I would expect the monsters in the toughest ones to be nerfed lightly or even perhaps none at all. If the design is that no one should expect to clear all ubers with the same build, this increases the design space to make the top 1-X of ubers that Marco likes the most a true challenge.