We have to concentrate on what we know and don’t know in regards to another duel.
Yes, we are clearly going to get another duel.
It could be a PTSD vision of Obi Wans. It could be a force vision. They bang on about fear all the time. Maybe OWK sees this as a force vision and he has to overcome his fear to do something important and this rematch never happens outside of his head.
Personally I think that if we do get a duel it’s going to involve Obi Wan ‘‘throwing the match’’ to make it look like he died, if it happens of Mustafar then we get more of that rhymetry that poems that they like so much. If Vader thinks Obi Wan is dead there’s no reason for him to keep looking for him and he can safely go back to Tatooine.