They're quite probably profiting from EU sales with the 120GB but were losing 18 dollars for each one of those in the USA due to the weaker dollar. So it makes sense they're letting the stock dry up before introducing newer Slims with cheaper components that will at last put them at break even or profit point.
I don't see it as a big deal having shortages when Heavy Rain releases, but it will be an enormous chance for great sales wasted if the situation lasts until GoW3 is released or past that point.








