There have been no roadmap updates since the initial announcement
You posted the link where you would see any updates if there were any.
As mentioned in other threads, the Roadmap is more of an initial placeholder where we will be adding updates as we move forward with development. We are in the extremely early stages so there is not much to update at this time. Don't worry, the Roadmap will start getting action soon.
Can I ask, is this weeks, months or years away?
Just trying to work out if themes will be added to 2.x, do I spend much time now theming core files in 1.15.2.
I do not think that you will get a response on when.