My cynical take on the UDH is that 12=speed derailleurs (and their conventional hangers) are too fragile, so the "industry" (SRAM) unilaterally decided on a bandaid fix, rather than backtrack to more sensible, robust 11 or 10 speed gearing.
Seeing as 11-speed gearing on a touring bike is considered by most to be too fragile and radically innovative, I think it is safe to say you won't see UDH on touring frames until 12-speed becomes the norm, which means not in our lifetimes.