I think this is a very plausible concept/rumor.
Personally, I think Apple should take all of their laptops into a more "Air-esque" fashion. Thinner, enclosed battery, remove the optical drive, less ports . . .
I would be first in line for a 15 inch MacBook Pro Air. But, why does "thin" equal "weak"? Is it an issue of CPU heat dispersion? Thin does not allow proper air flow?