I'd personally like to see Regions - Southern, East Anglia, Midlands, Northern, Great Western. Within the regions you'd have sectors - e.g Southern (Western, Central, Eastern), Midlands (East, West), Great Western (Thames & Chiltern, West Country), etc, etc.
Intercity - split off and run separately (EC, WC, Midland, XC, GW).
Regional Express - could be a brand of premium regional services with an GBR enforced set of standards, but operationally part of their own regions - I'd include Notts-Cardiff; most TPX, Norwich-Liverpool, maybe EWR, Euston-Crewe, Norwich-London, etc.
Devolution - I'd have more of a Transport for X-GBR alliance with their respective region, rather than LO/Liz Line style. I.e. agree a set of standards, min frequencies, staffing, maintaining GBR integration, but also with the services covered by the respective local transport authority.
Railfreight - DRS is nationalised right? Consider commercial expansion (maybe buy out a profitable foreign operator, bring some money in). Would've said rebrand to GBRf if it wasn't taken...