These number seem WAY LOW to me:
I can see Apple selling 15-20 million iPads per year. I can also see 50% or more users eventually buying iWorks because it makes the iPad so much more versatile (and laptop-like).
This translates to $225-300 million per year.
Add to this the inevitable major upgraded versions (most likely not free) and you have the potential for many times more income than this "Silicon Alley Insider" has predicted.