Merlin exec Julian Murphy has promised that the show will grow more "sophisticated".
The writer / producer told CultBox that the fantasy drama's young fans have grown up with the series.
"As happens with many of these things – I guess Harry Potter being the most famous example - you do take the younger audience with you and to keep them you need to offer more sophisticated fare," said Murphy.
The Merlin co-creator also revealed further casting details for series five, confirming that Alexander Vlahos will replace Hugo star Asa Butterfield as Morded.
"We're happy to officially say that Alexander Vlahos is playing the older Mordred," he said. "He's in a lot of [the fifth series]."
Murphy added that new episodes of Merlin are again likely to debut in the autumn, following the October 2011 premiere of series four.
"We expect to be pretty much where we were last time, up against The X Factor," he revealed. "They don't tell us for certain until very late in the day, though!"
The BBC recently revealed to Digital Spy that Game of Thrones star Liam Cunningham will appear in the new series of Merlin.
