Tons of video games still and will always have medieval & fantasy elements. Games like Warcraft and Diablo are another example.
Warrior wearing armor plate, shield and melee weapons, blacksmith, castle, fortress, wizard, ... Who the fck would actually say kids today aint into these kind of themes?
Zelda BOTW sold over 20 million units and its has big medieval & castle/kingdom elements. Yet, Lego never think of reviving Forestman theme.
Now if Lego only aim for 3-8 year old kids then yeah, they might prefer something like chima & ninjago.