I don't know about anyone else, but I'd love to see a 16th-17th Century Castle/Pirate theme, kind of along the lines of the sadly demised Imperial Armada in the Pirates line...
I figure there's plenty to work with in that era that would appeal to kids: I.e. have the Kings Musketeers battling to save the King from the Evil Cardinal and his Vile Henchmen, you could have something loosely based on Cyrano de Berjerac, a Merchant of Venice set, another set with the crazy Spanish Knight and his Trusty Squire vs the Evil Windmill (
), or from a more contemporary look at the era: The Dread Pirate Rodgers who seeks to rescue his One True Love from the Evil Prince. You could even have Cardinal's Guard and Musketeers Battle Pack (All for Fun and 5 for a Dollar!)
....Just my two cents, though.