Anything like that would require the participation and buy-in from all the other realms.
Now that so many southern realms have become influential in SA, I don't think it's really possible for any realm to become the heart of SA that Corsanctum once tried to become. I doubt you could get the buy-in from enough people to centralize authority in such a way. Too many people from too many wide-spread realms are in power.
Although... if there were a big crisis that required some strong central authority, it might be possible to get enough big wigs to agree on the need for a geographically centered central authority. Corsanctum would be ideal for this.
