I'm glad its not a reboot, too. 'Predators' can be an official sequel without Arnold. Unless the story hinges on Dutch somehow, but just like 'Predator 2' it can be rewritten to omit Arnold, after all he was supposedly going to be what Busey became and fight the Predator with Glover.
Interestingly, in the special features of Predator 2, Busey claims (probably not canon) that Dutch died several months after the first film.
I have my DVD collection as such:
Predator
Predator 2
Alien versus Predator
Alien versus Predator: Requiem
Alien
Aliens
Alien3
A:R
...I'd probably put 'Predators' in the order it is set, by date, as I do with everything else. Either after AVPR, after Predator 2 or after Predator.
Its only after you do that with a franchise and then watch them order that you see how absurd some prequels are.