No plans at the moment. Seems pretty fragmented with it split between kinds 21/22 and 34235/34236. Both of which not many clients support. Seems easier to just keep using kind 1 that keeps it interoperable with all clients and means greater reach for people’s videos.
Discussion
It's definitely early for those video kinds. Even clients that use them hardly fill any metadata (thumbnails, duration,..) atm. I'll continue to build on 21/22 ... let's see.