SilverWook said:
If they could make Jeff Bridges younger for Tron Legacy, aging Ewan to Alec Guinness' age in Episode IV ought not to be a problem. It might even be possible to resurrect Alec the way Marlon Brando was brought back for Superman Returns.
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The young Jeff Bridges looked weird in Tron Legacy. Not bad, just not quite right.
However, after watching the work that was done with Chris Evans in Captain America, I think they could make anything work.