@SteampunkTahu I came here to say exactly the same thing
To elaborate further though, Rebooting Knights kingdom would be great, the medieval/fantasy theme is an evergreen one, the characters have eyecatching colours, Knight armour would translate really well to a CCBS technic hybrid, and there's not so many of them that it would cost an arm and a leg if they were the same scale as say the 2015 toa. (being a lego owned theme also helps there)
The theme also had the right idea of having the main characters as consraction sets that were the centerpiece, while the story was told through system sets.
Speaking of the story, if it were to get the attention that Ningago or Elves does it could be just as successful.
In short, bringing back Knights kingdom as it was but with modern build techniques is what I want out of a constraction theme.