I understand the worry and see the threat.
I am hoping it does not manifest. Drug companies cannot just rest on their laurels because once their drugs are off patent, their profits go way down. So they have to keep coming up with new drugs. Unfortunately, sometimes they skimp and simply change one little thing so they can patent the same drug with one itty bitty change in it. However, that new drug may not have the same benefits as the original. It's very complicated.
OTOH, a lot of new drug work, R&D, is going on in Europe and elsewhere so you'll still see new drugs coming. Oh, and the drug companies with their billions will figure some way out of the box. Trust me, they're very inventive.