What I'm wondering is, assuming that not every individual operator will remain a standalone operator, e.g. Greater Anglia and c2c will surely at least both be something like Great British Railways -- Eastern -- or something like that, at what point do we stop using the current names c2c and go forward with the new ones?
I do think they should avoid making too many sub-brand things. So many operators could share one. Southern, Thameslink, SWR and Southeastern could ALL be "Great British Railways -- Southern", for example.
I have a gut feeling the likes of LNER, CrossCountry and Avanti services won't get a little end tag/suffix at all. I bet you're all hoping for "Great British Railways -- Intercity" and perhaps they might, but I have a feeling the Intercity services will just get Great British Railways with the suffixes saved for distinctly regional operations.