Of course sand doesn’t have to mean they’re on Tatooine, but I agree that it could be Force vision. It wouldn’t surprise me at all if this whole “rematch” deal turns out to be a bait-and-switch for the sake of marketing. But, for all we know they might end up doing both; i.e. a Force vision early on in the series as a bit of a teaser and an actual duel on some other planet at the end which convinces Vader that Obi-Wan has been killed…or something to that effect.
I am hoping for this too. A Force vision, a bait and switch, something included to keep the marketing people happy.
A little surprised we haven’t seen a full trailer yet, with only 6 weeks before the first couple of episodes are aired.