I think CDC himself once mentioned, as did someone else on this forum, that the original McCombs stadium was designed as a "double-decker", but that plan was scrapped before construction started. What this implies is that the foundation was designed (and poured) to take the weight of newer, bigger steel columns to support an upper deck. This two-fer would also provide shade to the lower decks as well as solve the answer as to where to put a new stadium.