Maybe Cat101 where you're a cat and you're fighting the main predators of the cat(dogs, humans ect.) You can be the domesticated cat or a wild cat(Lions, Tigers, ect.)
There's still an aircraft from Marleybone in Pet Pavilion. What if players could ride it to get to another piece of land, where there'd be plenty of space for new games? Perhaps it could even take players into a skyway, similar to Pirate101, tying both games a little closer.
I would suggest something like Barbarian101 or Guardian101. In Guardian101 I would believe it would be like the police of the Spiral or something where your characters goes by world to world solving crimes for the citizens of the Spiral.
And well I think you can guess what would go into Barbarian101.
Everyone seems to be assuming that a sequal to the game would put you in Pigswick, however there was another school of magical arts in the game. They can creat one where you live about 100 years before the fire titans attack on Dragon Spyre. Think about it, you'd still get trees to go with each class. Remember Ashley?
I have an idea that I've always wanted to see. It's called "Parkour101". For anyone who doesn't know what parkour means "the art of movement". It would be a game where you enroll in a school that teaches you different parkour moves. As you rank up, you can learn more advanced moves. Instead of worlds, there could be different towns. To get to new towns, you can compete in parkour tournaments. There would still be character customization, and the clothes would be urban clothes (if that's considered a category). You could explore an open world and parkour your heart out. This probably won't be created, but it's a pretty good idea in my opinion!
What about dragon101? That would be interesting. You could be a dragon tamer, like Hiccup in "How to Train Your Dragon". Or maybe you could be a dragon. There could be 3 main dragon types (kind of like w101's "elemental" schools") - ice, water, and fire, and then under each of those, you could choose what species of dragon you could be, like maybe a wyvern.
If Dragon101 becomes a thing, can you be able to train Toothless?
Wizard101: The Pigswick Chronicles - take on the role of a Pigswick student.
AND!
Wizard102: An expansion on Wizard101 where you import your 101 characters and they're made a bit older, then you work to earn your doctorate in your chosen school.
I absolutely love the idea of a Medieval101 :D Especially since Game of Thrones is so popular right now, I think KingsIsle would do very well with a Medieval101