The longer-term implications and changes will clearly require a great deal of planning and foresight. That means it's probably his duty to the state and to Abadar to boost his Cunning and Wisdom with Wishes, and then to spend a long time under Time Stop conferring with other wise people.
Being a cleric of Abadar is treated as a contract where He grants you power which you commit to use to advance your shared goals. The contract normally expires on death; Abadar can then propose to re-empower His petitioners in Axis, under new terms.
It has not escaped Khemet's notice that the abundance of Wishes means people might no longer die of old age. Even if he doesn't know how it could be done, exactly, it doesn't seem the kind of problem that would stand up unlimited magic (unless Pharasma decides to object).
This would not change clerichood very much; people can already terminate that contract at will. Being pharaoh is nominally a contract of the same sort. There have not been enough pharaohs in New Osirion for one to decide to abdicate, but the law allows it in principle, although the pharaoh's lawful duty to the state might override that if the abdication stands to do harm.
He considers proclaiming that the pharaoh will not seek to prolong his mortal life. It won't be abdication of duty if it's announced long in advance, and there are potential benefits to term limits. Such a law might be seen as setting a precedent for other Osirian officers of state, and high society in general, so he'll need to discuss the possible social effects with his advisors. ...under Time Stop, with elevated Cunning and Wisdom, and once affairs have settled down enough to consider social effects at all.
Khemet firmly reminds himself that this is the best day in Osirian history, and that he was the luckiest man in the country even before that, and refocuses on the meeting at hand.