That's it, really.
It might be difficult to recreate Fallout's Wild West feel, but I'm sure there's enough history and culture there to mesh with the Fallout vibe. And it's such an iconic city.
And it would have be done properly, with good voice actors & lots of local input in order to avoid the crass stereotypes that you too often see in depictions of 'merry olde england'.
So how about it, Bethesda?