A simple answer to your question is, most likely nothing will happen to your main account.
If we look at Niantics previous AR-Game title, Ingress, we can collect that they do not ban via IP addresses.
Niantic has been collaborating with Nintendo now though, so they might implement different Anti-Cheating measures.
But in reality, Niantic seems to be in-charge of Pokemon GO, and the Anti-Cheat system will be similar.