@Muah:
gay alert ree roo ree roo. Is that the sound a gay siren makes?
Only way for that to happen is if the end of one piece somehow became filler. It would be just like the end to movie one. Why would a pirate search on raftel for freedom? If he got to raftel that mofo is already free enuf. He's going to be expecting some actual treasure.
If Rogers did that than it would basically be
Lets see, the core concept here is "With great power comes great responsibility", when Luffy reaches Raftel (and be crazy strong) and learn the true history, he would undoubtedly come to realize that there is still stuff that needs to be corrected and that he, as the Pirate King, is now responsible to do that. You can't be free when you have responsibility, therefore in order to create a world where others are free, he would have to fight the greatest evil (maybe WG, maybe revolutionaries). At least thats how I imagined it.
Roger became ill and couldn't do that himself when he finally became strong enough, so he urges others to try and reach the end of grandline to find someone (remember Crocus and WB saying that Roger was waiting for someone?) strong enough to finish what he couldn't and thats where Luffy comes in.
The series focus has always been that to a noble man, treasure is not gold or materialistically valuable things, but things which one holds dear. To Roger; who could hear the voice of everything, who created the great age of piracy, and who is described to hold a similar personality to Luffy; doesn't something as basic as the philosophical truth regarding freedom seem fitting to be the greatest treasure worth risking your life for?