That said:
1. Apple is pointedly not afraid of cannibalizing its own markets.
2. Apple is pointedly thinking in terms of "the Mac should respond to the iPad as a competitor" and this basically puts the iPad + keyboard case directly in competition with the Macbook Air (expect the SSD capacity of the Air to be reduced or the iPad to increase -- no way a 64GB Air sells for the same price as a 64GB iPad).
3. Now that the Mac is decidedly not central to Apple's revenues, expect Apple to rethink its Mac pricing in (to competitors) scary ways. Apple can afford to license its OS to third parties, and/or replace the Mac Pro with a dongle-based OS X license (buy whatever beastly workstation you want, and install Mac OS X Workstation Edition on it).
4. Apple really has no-one to compete with but itself at this point. Its competitors are a joke.