I'll tell you what - I got to use an F6 and WOW! It's a really nice camera. Handing the F5 it's posterior in every way. I think the price is way too high, but the camera itself was amazing. It's deviously heavy for it's size, but is ergonomically perfect with a nice balance even with heavy glass.
I think if Nikon plays their cards right, they will allow the F6 body to be adapted for digital - a hybrid if you will. I didn't study the camera to see if it's possible, but I'm sure it is somewhat feasable. That would be the only way to really justify it for most people as most industries have moved to digital. They are selling though, so I guess the rather minimal R&D costs made the F6 easy to create being that most of it's tech was created and the cost absorbed by the D2h and forthcoming D2x.