Well, the thread you point to is about 64bit support (and indeed also mentions V3D on 64bit) … I dont plan to work on any 64bit images. The ones I built are for initial developer use until an official Ubuntu image exists.
Wether or not @ppisati plans to work on a 64bit kernel for upcoming official Ubuntu Pi4 images and when the Ubuntu kernels will be ready at all, I dont even know though.
Im a strong opponent of supporting arm64 on unsuited hardware.
64bit ARM means you allocate nearly twice the ram for each running application without gaining any beneift, unless the app actually makes use of 64bit registers… so effectively you only waste memory. It is a hard requirement on systems with more than 4GB of ram and it surely makes sense for software that has been specifically written for 64bit register usage though.
What i plan to work on in the nearer future is a classic image to provide along with the Ubuntu Core image though (but under the same restrictions, only until an actual Ubuntu image exists).