A roadmap is a plan, not a promise
Years signal the order we intend to work in, not a delivery commitment. Planned items are ones we have decided to build and understand well enough to describe. Exploring items are ones we think are right but have not proven yet, and some of them will not survive contact with real usage.
We would rather list four things we finish than fourteen we announce. If something here matters to your business, tell us and it moves up — the order is driven far more by what buyers and publishers ask for than by what looks good on a page like this.