Not interchangeable in the least, but that was not the question, if no Banega, Pastore could fit well into my proposed 4-3-3 idea.
With the way the guy is playing right now, the Argentine FA need to find a way to bring Messi's club form into the national team. Give him a freelance role, make him the focal point of all attacking plans, bring back Riquelme, Hire Guardiola as assistant, heck, get him to wear a Barca shirt during WC matches.