Since Ambisonics is “speaker array agnostic”, VST3 doesn’t necessarily need more Ambisonic speaker mappings, but it needs to handle Ambisonic orders adequately. The referenced post does talk about Ambisonic orders up to the 7th (64 channels), so it should be good news to Ambisonic plug-ins developers like Aalto Sparta and IEM.
Let’s also note that the next version of Pro Tools Ultimate should support Ambisonic bussing up to 7th order, so there’s some commercial pressure there for VST3 to get its ducks in a row regarding adequate Ambisonic support.
While I’m always happy for better support of things, I do have to question how much something like 7th order ambisonics really matters. Equipment required to hear the improvement aside, the load that doing 64 channels puts on a system is a lot. Any effect you drop on a bus line that is having to run 64 times in parallel more or less.
Like you can do it, I know of things made in Reaper in 7OA, but you aren’t going to do a bit complex project without a boatload of bouncing (and thus a boatload of disk because each bounce is 64 tracks).