Also Ripsaw, the Flume and The Blade were suggested in the LTDP to be removed along with the the new gloomy wood entrance (something which I am against as I feel that A the area would be too crowded and B it is nice walking in looking at the towers). So even though it is just speculation, they are educated guesses going off of previous knowledge of what Merlin are like and the LTDP which was released by AT.
CCL, Duel and areas around FV were all highlighted as areas for development which so it could be likely that SW8 goes in one of those spots. Also I think a large scale dark ride was mentioned in the LTDP which reinforces the idea that SW8/9 will be a duel replacement, although it could be a whole new one and Duel could just get a revamp.
I think SW9 will be the dark ride. If it was in/on Duel then surely Duel would be removed at the end of this season. Also, if FV needs a revamp and SW8 is a speculated B and M, I think the ride could go there to boost the amount of people it attracts. I'm sure someone said Nemesis and Air don't get the queues they deserve, so why not?