IMHO there are lots of curious althistorical scenarios here, such as the one that you have mentioned. The NOD, however, was not created to counter the GDI, but instead I had intended it as an alliance against Japan and Aztlan, and in perspective Scandinavia and the Iroquois. Ironically the latter two later became allies, more or less.
What if my anti-Iroquois coalition building (when I wrote a long PM to try and get the Celts to leave both the GDI and the ASP, instead joining the NOD and ganging up on the Iroquois with us) had worked? Byzantines and Mayans would have been able to advance their imperial ambitions freely (no Iroquois intervention, which would have made things easier for them), whereas the NOD and Celtic forces would have been fighting a huge war with the Iroquois.