Cannae is certainly a significant event but keep in mind rome was split between its traditional method of fighting war, i.e. the pitbull method and the new Fabian method. It was the concilium plebis that set Cannae in motion. Only after Cannae did the romans strike the balance between Fabian and pitbull.
Certainly many of the future millitary leaders were at Cannae and learned great tactical lessons, but strategically? I don't think so. Hannibal's flaw was that he failed to appreciate the romans socially, politically and economically. Tactically he knew the romans and used their strength against them but had he fully appreciated the other factors he's have known his venture was doomed to fail. The strategic moves undertaken during the 2nd punic war, other than the initial move by Hannibal, were all conducted by the romans in Spain, Greece, Ilyria, Sicily, and North Africa. It could have been a different story had Hasdrubal not dalied in southern Gaul throughout the winter of 208 when Marcellus had been taken care of but he did. Even if he had not perished on the Metaurus and met up with H in southern Italy I believe roman victory would have been the ultimate outcome, it would have taken longer and been more desparate, but without a seaport H was in trouble.
Nova Carthago certainly has its merits too. It must have been a fantastic shock for the Carthaginians to learn they'd lost their spanish capital, their main arsenal, and their main port in one swoop.