It’s been discussed by some. The OS is likely to release some data, but under what terms remains to be seen.
Free usually means gratis, while in the context of OSM it means libre.
Assuming they release the data under the most liberal license possible, it would be great to have up to date parish, district and county boundary data and electoral ward boundaries. The latter are almost impossible to derive from out of copyright maps. I have added some electoral boundary data from my own knowledge of said boundaries - I’ve stood as a candidate and been involved in local politics for several years. However it’s extremely unlikely that we could gather a complete set of electoral ward and division data and so if the OS makes that available under suitable licensing that would be a big step forward.
Sadly I feel it’s more likely that they will release it free (gratis) for personal use only.
They’ve expressly said that commercial use will be permitted.
My guess is that they’re going to release Meridian2 or something similar, which is a street dataset plus boundaries, rivers and railways; and that it’ll be under a revised version of the Click-Use PSI licence, which is tending towards public domain.
6.2 It does not otherwise allow you to authorise the reproduction of the Material
6.3 Translating the Material from the English, Gaelic or Welsh language into other languages, provided that the translations are accurate and made by a competent translator
9.9 … not present your version of the Material as being the Official Source, for example by replicating the Official Source’s style and appearance - Some elements of OSM cartographic style are very close to the Ordnance Survey style.
9.10 … allow us to inspect copies of any works which include the Material to check that you have kept to the terms of this Licence.
I imagine these are the sort of things that you had in mind when you said “revised version” but I am interested if you think the eventual license will be OK for OSM purposes?
If so, the boundary data will surely be extremely useful.