I don’t foresee that stopping either. People are going to chase the best loot (often when they are undergeared). M+ is far more accessible than mythic raiding so that is where they are going to go for it.
If you trim access to that loot down to a single key level then that is where people are going to flood to attempt to be carried to that loot. If you open it up to another key level then you significantly reduce the people who shouldn’t be in 10s that are applying for them.