This is a question that sometimes comes up, and I'm interested in knowing what everyone's thoughts are: how would Merlin ever be able to help Arthur again, if he came back, given that he was locked away in a tomb forever?
It seems that most works which address this issue take some artistic license to indicate that Merlin wasn't locked away forever. The Last Enchantment by Mary Stewart had Merlin simply sealed away in the tomb physically, and later be discovered by someone who is able to get him out. The animated series and comics Gargoyles never addressed Merlin specifically, but did deal with Arthur's returning, and indicated that he was looking for Merlin. The 1998 miniseries Merlin reversed the story and had the Lady of the Lake be the one who was locked away, while Merlin lived out his life waiting for her outdoors, until the magic that locked her away finally faded.
What are everyone's thoughts? Is there any way to resolve this without taking artistic license?