As Jon81 rightly says, and as many have been saying on here for years; AT is packed with coasters, especially when you consider the location and environment that it's situated in. Flats can be good, and agree that Talocan is proof, but often they are a little repetitive and hard to fit in to the theme park experience. Dark rides, entertainment shows, fun houses, and even shops are what do provide this; which is exactly why Talbot and old Towers Street worked so well. No rushed, marketing obsessed decisions and instead an imaginative approach that focused on appealing to all guests.
Duel is an insult when you consider what it used to be, except for the new music perhaps. Complete misuse of UV blacklighting which clearly emerged from minimal consultation, aging props, and the shooting concept really isn't all that anymore; it was always a fad, but at least it gave some life to the place for a while and made it marketable. Huge work is needed, rather than the money wasting that has taken place recently over the last few years. That is more important than a new secret weapon.
A new dark ride is needed to replace Sub Terra, which could be SW9. Something substantial without actor reliance, an indoor boat ride perhaps, or even something tracked.
But the main site for SW9 would hopefully be replacing the awful Dungeon and the slab wood wall around it, which I personally will never set foot in. You could fit a nice indoor/outdoor flume there and re-purpose some large buildings in the process.
Naturally skeptical of course, as we all know Merlin and their track record, but that doesn't mean we can't idealize what we think should happen.