It often feels as though the Champs Elysees finish as been around forever, like the polka-dot jersey. In fact both were introduced in 1975.
Prior to that, the lead certainly changed hands on the final day road stage in 1947.
In 1979 Joop Zoetemelk, over 3 minutes behind in second place, successfully beat the entire field on the Champs Elysees by more than two minutes - apart from the leader Bernard Hinault who beat him in in the final sprint. As they were both almost half an hour ahead of everyone else, I suppose the rest may have decided not to chase in recognition of their superiority.
More recently, I can remember Pedro Delgado making attempts to get away in 1987, when trailing by 40 seconds.
It's not unusual for there to be time losses due to splits in the field on the final stage, though the 3 second rule might make it less likely. I think the so-called tradition is a myth. If the situation were right, as it could possibly be this year, I think they'd give it everything hoping for a split at the right time.