Don't know that I agree with this. The pro apps exist to fuel sales of their semi pro (like the quad iMac) and Pro (MPs) machines.
I agree with your statement but Erik's point is still valid. Apple pushed FCS in order to build an ecosystem around pro Macs and OS X. This was all pre-iPod. Now Apple is earning a much larger percentage of it's revenue from iPhone/iPod and laptops.
They've said for years that most Mac sold are notebooks.
As they move to more of a consumer electronics company we really have to wonder if they need the Pro market and if the cost of developing/supporting Pro apps brings a large enough ROI for Apple.
I wonder if a FileMaker/Claris type spin off of the Pro division would work for both Apple and customers?