We learned a lesson or two on recall compatibility with the last bigger Nova update. We'd definitely make Nova "next edition" a whole new product, not directly compatible with older versions (although we'll maybe add settings transfer options via copy and paste).
About a multi-arbiter, we are already planning to add a few more bands in future updates (but it's less trivial than it looks, because arbiter's algorithm depends on the wideband input, it can't be run in parallel that easily while still making sense musically).
We also have a rather exciting idea around Arbiter to be disclosed later, but still subject to prototyping, not really sure it works as envisioned (no AI or auto mastering, in case someone worries already
).
In any way, the point is that Arbiter will develop quite a bit over time and eventually reach a state close to Nova's operational depth. I agree it's likely wiser to keep these concepts separate (they really are fundamentally different).