After Morgana was killed, Peace was restored back to camelot. Merlin returned, Gwen thanked him for watching over Arthur all these years, and to reward him brought Magic into the kingdom, making a new albion, where magic was accepted and not outlawed, as was prophesied. Merlin continued living with Gaius, going frequently to the crystal caves to visit his father, and perhaps Arthur? He stayed with Gaius, using his magical skills to heal ailments and battle wounds. After Arthurs demise, he had alot of time to kill, until Arthur would 'rise again,' so he learnt alot more, including going back and forward in time, which is how he came about at the end walking around england in the 21st century (i'm presuming.) Maybe Gaius spent more time re-learning all his abilities in magic too, now that magic was not taboo anymore. And was able to help Merlin become a better sorceror then he already was.

What would be YOUR ending?