But I think that one of the "greatest storytellers of the modern age" would be someone more like Quentin Tarantino, Chuck Palahniuk or even Kevin Smith. Darren Aronofsky has written some great movies aswell, but I think it's more his filmstyle that makes them great and not the actual story. Pi would be a boring book to read, but it was a genius movie to watch. Chuck Palahniuk writes some of the greatest books ever. Survivor being my favorite of them.
And I don't really think anyone will ever create the "most wonderous story ever told." I mean, to do that, it would have to be something so good that everyone in the world (or at least everyone who's watched/read it) would like. That's impossible to do, because everyone's opinions are so different...
Though, I do agree that future writers can learn from Lucas' mistakes.