In the case of Photoshop you're going from $1300 up front to $50/$35 per month. That's a huge difference in affordability, so I'd be surprised if that wouldn't make a dent in piracy, particularly in small businesses.
I know a lot of people 'want' to pay for the software, because they feel it's the right thing to do. A system like this will help them to do the right thing.
Personally I go open source as I don't want to pay that amount for an image editor. On principal I paid for software from the day I could afford it, given that I make money from software. I find it makes me wince slightly when friends and clients ask me where they can get office, photoshop and cs5 for free. Would they pirate my work if they could?
So I don't use adobe on principal as I see their stuff as a total ripoff. Not very good either, I tried the trial version 6 months back, while better than GIMP/Paint.Net it's still got a pretty awful UI.
The only annoying thing is that a lot of people send you PSD files, so I sometime have to fire up another trial just to export certain layers easily. There are some plugins available for this but they are a bit cumbersome last I checked.
I'm always a bit surprised that none of the major software vendors with the muscle to put a few hundred developers on a new project for a couple of years have tried to break into the graphics/DTP market that Adobe dominates today. Given their reputation for poor quality and usability, it's not the most defensible position for Adobe to hold against a competitor with good developers and talented project management/vision people.