is it just a case of the bugs and beasties have evolved so that they can have their wicked way on the Cotton?
from that I can assume that all other GM crops will go the same way?
It'll happen, sooner or later. Then the crop scientists come up with another genetic modification until the critters catch up again. It's an arms race like in the good old days of the cold war. Same with antibiotics. However, there the retarded use of antibacterial soaps, prescription of antibiotics for idiotic reasons (like a viral infection where antibiotics have zero use) and the improper use of antibiotics by the patients (stopping early in the regimen, taking them not in the prescribed frequency, etc.), is only accelerating development of multiple resistant strains.