Mmmm, Virgin Teens. PIN lock and £5-a-night to watch that channel then?
In all seriousness, I will be very surprised if they have not thought about it, and in time I reckon they will do it. VM clearly has aspirations to be a pay-TV provider with national reach and brand recognition, which is why they are launching Freeview boxes (and it's a dead cert that each box will have a card slot for future delivery of extras).
As for why they didn't do it before - well, this time last year the channels were owned by Telewest, who as a modest-sized cableco had nothing to gain by pushing its brand in that way. NTL, in true short-sighted NTL fashion, spent months trying to get Telewest to sell the channels as a condition of the merger, so it was hardly likely to be a priority for the merged company.
But with Mr Branson now on board (and believe me, I know for a fact that his denim-clad, laid-back emissaries of all things informal and beardy are crawling all over the VM operation, trying to infuse it with their master's unique corporate values), and with the company in a long-term war of attrition with Sky, the Flextech channels have just become an extremely important strategic asset.
It would be difficult for Sky to muck up the EPG were VM to demand the channels be re-named, as VM has paid for the channels to be there and will have a legally binding service agreement with Sky that is bound to cover such things (the UKTV channels subtly altered their names in the recent past, which Sky didn't seem to have any problems with).
They may not go so far as a full-on renaming spree, but references to Virgin in continuity announcements, altered station ident logos, and perhaps new names for some of the channels - I think we can count on it. And if they don't resolve the issue with Sky One etc soon, I think we may see it sooner than later.