The wikipedia entry below says that Merck stopped manufacturing while waiting for regulatory approvals, which chimes with the first post in this thread.

However, Merck(MSD) has not answered any questions with any significant clarity.

If this becomes a significant problem for patients in the US and you are personally affected, or have concerns I suggest that you contact your patient orgs and ask that they request an answer to these questions:

What regulatory approvals are Merck (MSD) awaiting for, and where?
When do they anticipate the approvals being made?

http://en.wikipedia.org/wiki/Carbidopa/levodopa

I would also pass this info on to patient groups or anyone you hear of who is affected:

Please be aware that generics can vary both upward and downward in their levodopa content. If you are changed to a generic and have not used one before, be prepared to have to readjust your medication to take account of the difference. Please discuss this with your neurologist/doctor.

This has affected a lot of people globally already.