So a lot of people don't like the new style of 20 man mythic. We're all trying to find alternatives to this.
The only way to stop 20 man mythic is to stop comparing 10 and 25 man raiding as if they were the same thing
10 man does not equal 25 man. Nor is one better than the other.
Neither are harder than the other, neither are easier.
Heroic is hard content no matter the number of people you have.
Some bosses are "easier" on 10 or 25, some are harder, that's just how it is.
If you want to not have 20 man Mythic, the only way to change that is, as a community, stop the stupid hate between the two difficulties and just accept them as two different entities. Stop that, and blizzard might not see the need to squish it together.