I think there is a market for TWH trail horses already, at least in the west.
I frequently see people asking $5000 or better for gaited horses like Foxtrotters and Walking horses. And I don't mean show horses, just trail horses.
I totally lucked out and got a 15yr old Foxtrotter mare for $500. But I keep hearing about people who go back to Missouri or Kentucky or whereever and bring back trailer loads of gaited horses to sell out west. That's kind of the story with my $500 Foxtrotter except she was used as a rental horse and broodmare for a while, so I guess they didn't feel like they needed to make more off of her. They told me they were selling off their mares. They had a bunch of different breeds and grade horses, so I don't think they thought the gaited horses were special, just trying to sell off some excess horses.
My neighbor whom I ride with who has Foxtrotters and a Walker, when she lived in California, knew a guy that would go back and buy gaited horses to resell in California. So, at least in the west, gaited horses usually cost way more than say an average trail horse.