With the removal of Corkscrew, Alton definitely need a straight-talking coaster which reaffirms to guests what the "norm" is, upon which crazy coaster variants such as Air and Thirteen are based. They need something with a bit of force, something that really throws you around, as opposed to something which you have to "get". I'm not saying roller coasters with a bit of identity to them is a bad thing, its just that too much identity and not enough substance makes for disappointment (which, to some riders, is what Thirteen is).
So say they got a eurofighter (or something similar) minus the over-vertical drop (which would take the edge of Saw, and to a greater extent Oblivion), that delivers the thrills but may not be as visually striking as other rides. Why not, then, bung it in the tent? Darkness hides to the appeal and hides the fact that Alton are adding a coaster which may not be as technically superb as it could be. Afterall, technical superbness does not make a ride fantastic, necessarily, and any "worlds firsts" should be left to 2013.
The reason I go into detail here is more to put up an argument that we shouldn't rule out a coaster next year. It's unlikely, given 2013 plans, but still.