I wasn't aware that this existed until creators club, and I understand the reason it got buried was because GWR wanted to focus on the new brand. However, I wonder if they'd think differently now - it's now a different era, with all HSTs in Paddington being a thing of the past, so it fits with the nostalgic aspect of the route. I really think it's worth DTG asking the question - it looks so good and would be great to see it in timetable mode.
It really would be fantastic to have the HST and Class 166 in FGW Blue liveries as they were still occasionally to be seen at that time. A number of operators may also think differently in the coming months as I believe that wide ranging rebranding will commence soon with the launch of GBR as of 2023 and the current variety of liveries will likely be replaced making them a part of history. I hope that GBR go with a striking and interesting livery.
This is exactly the way I see it too. I think that GWR should see that the route is representative of the past now, and just add it as a nod to their past. I've always thought it would be brilliant as a mastery award, but I'd be just as happy if they just immediately released it. It's definitely worth DTG asking again. Oh, and don't forget the brilliant FGW 166! I saw one yesterday at Cardiff still in FGW livery and branding and thought to myself "if they can't be bothered to update their own trains over five years after they became GWR then there really is no reason NOT to have it in TSW2".