This is what I'm worried about too. The windows driver teams have hundreds of people on them from what we've heard, and the OSS developers are far fewer in number. It sucks for anyone to have to lose their job, but it would hurt the OSS dev group much more to lose someone (especiallly since I'm not sure that AMD even has 10 developers working on open-source drivers).
AMD has four people working on their free Linux drivers, and I am unsure how many are working on the Linux Catalyst driver.
However, I somehow doubt that they will be targeting the graphics team. I have no real knowledge to back this up, but even though they are now branded as "AMD Graphics", the graphics team as far as I can tell as an outside observer is still very much separate from the rest of AMD, being based in the GTA rather than Silicon Valley, focusing on different projects, and just being distinct from the rest.
Considering it is not graphics that are lagging in sales (AMD and ATI cards still dominate a large chunk of high end and consumer level graphics) it is my impression (and hope) that it is not from there that they feel they need to make cuts. Obviously any cuts anywhere are sad and awful (I like AMD CPUs just as much as their GPUs), but I would rather have the FOSS drivers keep going strong.