I just got this from two sources:
Source A: A source at Panasonic has told me they are looking at upgrading the DVX200 to include 10bit recording. This may involve a paid return and upgrade program, it hasn’t been decided yet. They are unsure if the internal boards and processor will need to be changed to allow this. Either way my source thinks an upgrade is very likley on the DVX200 as the GH5 is currently a lower priced camera with higher specs.
Source B: Two of my friends at CES heard from a Panasonic rep that the DVX200 is to get 10bit 4K internal recording, the rep did not say when or if it would be a new model or a paid upgrade, or any more details. Just that it would be available around the same time as it was for the GH5.