I have the feeling that the gold watch portion will actually be significantly smaller portion of the 5K price (if it is 5k) Something like $999 - $1999. The rest of the price will come in the bands at 2 - 4K each.
They still have to sell the watch itself with their margins however. There's nothing stopping you from buying an aftermarket strap, and if they require you to purchase a strap with the watch -- well then it doesn't matter how they split the price up.
If the bands are forward compatible with future generations, then it becomes more attractive to spend more on the band vs the face.