I have these same worries–mostly about our oil supply, and if that gets really pricey b/c of a shortage, we will not have such easy access to meds, or they will be unbelievably expensive. Eventually, medicine as we know it will end because our oil supply can't last forever, and some think the supply has already peaked–of course there are always the “sky is falling” mentality. Hopefully, the oil supply will peak later rather than sooner.
Also, on a forum once, and I don't know how true this is, so maybe a moderator can weigh in, a man said his doctor told him if he was w/out a thyroid, or had completely ablated it, he could live 2 weeks w/out synthroid, but if you have active graves, you could live much longer than 2 weeks w/out meds.
I have no idea if his information was accurate, but it's just plain out scary to rely on a medicine. These worries keep me up at night–which is probably not good for my graves.