Samuel H
Major Contributor
ThisThat is largely a hardware issue.
Which doesn't mean you can't get 10-bit through a firmware update, but it does make it very unlikely. For this to happen, you'd need to be in a world where Sony put 10-bit capability in the hardware processor (a non-trivial thing which adds cost to every chip they made) and kept it disabled in every camera that has shipped with that processor so far, only to then enable it via firmware. As I said: unlikely.
Yet again, last year Canon was still using the same video processor (the Digic DV III) in all its models, from the $300 vixia cameras to the $15000 C300 (the C500 was the only exception I'm aware of), and had its nice mpeg2 422 codec disabled in basically all of them.