I think the focus of Aperture is different than Photoshop (pun not intended). It seems geared specifically towards professional photographers. Photoshop is a much more diverse application than that, and has become a graphics and illustration program as much as anything. So I suspect Aperture won't have an effect on Photoshop, any more than Motion did on After Effects. Motion is a very specific application that does what it does very well, but it's not a replacement or direct competitor for After Effects - it's more of an additional app that fills in a few gaps. Aperture seems to be the same type of thing.
Final Cut Pro, on the other hand, was meant as a competitor to Avid, and by extension Premiere (but without its many flaws), so it pretty much killed Premiere on the Mac. Premiere (unlike Photoshop and After Effects) was a weak, buggy app. It may be better now on the PC side, but Mac users don't miss it. We'd miss Photoshop and After Effects, and so would Apple. People buy a lot of Macs to run them.