When Lennon died, the entire world listened to Imagine many times again because its message and because the terrible way that John died, and because he was really young at the time (and also just coming back after a 5-year break). When George died was really predestined, many people already knew before his dead that he was in trouble and his final was really coming. But if Paul dies at 90, for example, what we're gonna hear about him? He doesn't have any real 'signature' song as a solo artist, so surely we'll hear 'Yesterday', 'Let It Be', all those classic Beatle tunes.