@Knagis, there’s this list of issues to resolve before 1.0 which could be considered a roadmap. It does not include a timeline though.
There could be more indication as to the extension syntax that will eventually be adopted though. That way app developers can implement something now even if the precise details change later. Table syntax is a good example. There are current many different syntax variations to choose from. CommonMark could have a stance on this now, even if the core has yet to be finalised.