"I beat Morgatha and won the game now what do I do now?"
Make & level another wiz, farm or craft new and better gear, collect pets, PvP, pet derby, decorate castles, make friends, finish side quests, help other players... "Is there an part #3 ever coming in the future? "
You could give writing stories based on the game a try or maybe even fanart. It's not something that you can do in game but it can be fun and it might be posted on the wizard101 webpage if you submit it through E-mail.
As to the other questions I say, you'll just have to wait and see.
First question, well there are plenty of things to do! So much, that you are never bored! Crafting, farming, gardening, Exploring/ Sight-seeing or even just Plain Ol' PVP, there are loads of stuff to do!