It would be pretty cool if Zeppelin would do something. Aren't at least Page and Plant still alive? John Bonham is dead though. RIP They should play at Coachella or something.
Plant, Page and J-P Jones along with Jason B could, form a band but, just as with the Beatles, if the originals are no longer there any re-formation would be lacking. Legacy should not be compromised by the lack of former glorious unity and the passing of time. (at 69. 73 and 71 years respectively) . In this case although 'the song' may, the performance 'will 'not 'remain the same'
Funny how some bands can get away with changes in lineup but other bands can't. Fleetwood Mac and The Doobie Brothers, for example, have had fluid lineups with no problems I know of...but yeah, Zep and The Beatles could never get away with it.