The historic roots of string theory are in an explanation of the strong force. Nowadays QCD is the accepted theory of strong force. But having heard several lectures on the large N limit (SU(N)) of gauge theories it seems these theories start to looklike string theories in this limit. I believe this idea (that gauge theories look like string theory in the large N limit) may have inspired AdS/CFT...you take the large limit in the orginal paper i believe. One question in QCD is if 3 is close enoght to infinity to take the large N limit as a good approximation? If it is and we take use Ads/CFT we can then use string theory to do real QCD calculations even if strings are not fundemental. In this way Ads/CFT and string theory could be just useful calclation tool but not a fundemental description of nature. We could then be in a situation where QFT is still more fundemental than String theory or(more likely) they are both approximations to something still more fundemental.