Ya know, it is funny that people ask questions of the future without first consulting the past. Photoshop is approaching it's 20th birthday, which means we have two 10 year periods to look at when considering what the next 10 year period might look like.
In Photoshop's first 10 years the biggest changes for me were the inclusion of the layers and histories palettes. So for me, by version 5 (released in 1998) Photoshop was a pretty mature application. While there were a number of cool features added during the following 10 year period, 90% of what I use Photoshop for on a daily basis was present and accounted for by version 5.5... which I still make use of on an old PowerBook 3400c.
This isn't to say that I haven't upgraded since 5.5... I have. I bought 7 to have a Mac OS X native version, and then got 8 when I got the full Creative Suite Premium (which I actually got for InDesign and Acrobat 6 Pro).
I do enjoy most of the newer features (and demo them for people wanting to learn Photoshop), but the main tools... the ones I've used day in and day out for the last 10 years, are all pretty much the same as they have always been.
Are there feature upgrades or additions that radically effect how the application feels? Absolutely. I have a copy of Photoshop 3.0.1 on my SGI Indy (the last version for Silicon Graphics computers), and it is very difficult to use with things like the histories palette missing. And even though I can be very productive in Photoshop 5.5 today, when working with type it becomes quite cumbersome and I long for newer versions.
But will Photoshop be radically different 10 years from now? It's not radically different from how it was 10 years ago, so I would say no.
On the other hand, what you should be asking is if Photoshop is the right application for photographers going forward.
Photoshop was designed as a darkroom replacement, but even back in the days of film photography, most photographers spent very little time in darkrooms touching up images, and spent most of their time organizing and comparing large groups of images. Photoshop never attempted to cover this vital area of photography, and it was only with the advent of Aperture and Lightroom that photographers got the computer equivalent of what PageMaker was for page layout professionals (something that resembled the types of tasks they did in the physical world but within the computer).
So if your question is: Is Photoshop going to be the right tool for me to use going forward?, the answer will depend on what you plan on doing with photography. For most of the photographers I work with, Aperture and Lightroom are really the applications they have been needing all these years.
