We're still waiting on FFIII for the DS, but Nintendo and Square Enix are continuing the series on Game Boy.
Nintendo News: 'FINAL FANTASY(R) IV' Comes to Game Boy Advance SP
Fans of the legendary "FINAL FANTASY" series can rejoice. The fourth
installment of the wildly popular series will be published by Nintendo and
available on Dec. 12 for Game Boy(R) Advance SP and Game Boy(R) Micro.
The GBA version of this classic adventure includes 18 towns and castles,
dozens of magical spells and hundreds of monsters, weapons and items to help
players on their quests. The game features the astounding music, challenging
adventures and interesting storyline that are the hallmarks of the "FINAL
FANTASY" franchise. Additional game elements also have been added to enhance
the Game Boy Advance version.
Players can expect 30 to 40 hours of playing time as they journey on land,
on sea and in the air, and explore new towns, caves and mountains in their
attempt to recover stolen crystals. Twelve different characters with new
abilities, spells and items join and leave the party at different parts of the
quest to keep the game fresh.