Quoted from Nokoro:A few come to mind for me:
Minecraft: Enormously popular still (I think). This theme just screams for a pin. I can imagine the colorful pixilated artwork and images on an LCD, the toys, and the rules. It would be cool to see some rules and modes around crafting.
The Legend of Zelda: Another hugely popular video game franchise. There would just be so much you could do with this.
Wonder Woman: The recent movie was well received, and it seems like almost every other superhero gets a pin at some point.
Along those lines, Lego off of the first Lego movie possibly could be interesting, it had a lot of adult humor in it. Callouts by Chris Pratt.