User blog comment:TheSonofNeptune/The Seven's Hypothetical Futures/@comment-4727448-20131120043001

Percy and Annabeth will miraculously survive all the hell they go through and have children and die after kids reach the teenage years.

Percy will probably chill at camp. Annabeth will get some sort of civil engineering job. Jason will return to Praetoring, possibly with Frank. Frank will be some sort of professional bodyguard. Hazel will take care of horses. Piper will waste her days with Jason.

Leo and Calypso (assuming they survive, of course, as you said) will open their machine shop! :D

Hypothetically speaking, Camp Jupiter and Camp Half Blood could come together somehow. Camp Half Blood could look into permanent residence. etc etc