This is an emotive issue. But I think Steve needs to say "I am REALLY handing over to Tim now" to the Apple faithful. IMHO Steve and Tim will do whatever they think is best for Apple, in the long term. They will want iPhone5 to be about the future; not a symbol of the past.
How about this solution:
Steve walks out on stage - <big ovation> - then Tim joins him - and they both say "OK team. One more thing!" Then Tim takes out the iPhone5 from his pocket and hands it to Steve, saying "We got you this."