Final fantasy is awesome and given that Lego is looking into pop culture stuff, it would be a great place to start. The idea pretty much in the title make Final Fantasy Sets and Mini Figures from across all FF games.
Lego could even do some sort of random bag like their current minifigure sets.
Specific set/figure ideas:
-Minifig rideable Chocobos
-All the character classes from FF1 including iconic weapons like Fighter ♥ Swords! or White Mage hammer time
-The Starting Castle Area (just cool looking, make it overworld scale compared to minifigure size!)
- Magitek Armor
- Suplex a Demon Train
-Locke/Celes Opera House
-Highwind and various airships
Also Lego Moogles!
I can post concept art if anyone is interested.