Nah, I wouldn't follow it. By the time One Piece itself is done, Oda should have wrapped up all the mysteries and such. So then the question would be, why follow a series that is set in a world with nothing more to offer?
The only way I could see a sequel working is if it is set far into the future, not immediately after Luffy's generation. Oda could make it so that some event/cataclysm has reshaped One Piece's world or that the advancement of technology has allowed interstellar travel.
Other than that, Oda could probably do a successful prequel set during Roger's time.