Yes this is still part of the plan, and was perhaps not specified in the original post: runtimes should and will be controlled by the fellowship. I suppose this will be done after the mono-repo.
IMO It is hard to address that as it translates to doing a full engine repair while a car is moving. There is a tradeoff between development and stability, and many still expect new features to be shipped and we have to make a choice between the two. For sure we are closer to being at a stable position now, but we are certainly not there you.
That being said, this needs to be assessed at various scales. Making each crate fully independent, and semver compatible with release planning is something beyond any of us have the resources to do right now. I am trying to propose something like that just for the common FRAME APIs here: https://github.com/paritytech/substrate/pull/14137.
All in all though, I think the matter of releasing and versioning is somewhat decoupled in my mind. We can break the repo into smaller pieces, and still force them to stay in sync with companions and never have proper releases. And similarly, moving to a mono-repo does not necessarily mean we are moving further away from releasing. For further reference, see here about releasing: Publish Substrate to crates.io