Ok, this is just to kick off discussion, since this thread might languish otherwise, for the lack of ideas floating around.
I've got two plot bunnies running in my head right now, both revolving around possible crossovers.
The first is a more serious consideration, but one probably quite fit for Kirito, considering that he's one of the most competent LN protagonist out there. It's a Muv Luv crossover, which I will put in spoiler tags, for those who haven't yet spoiled themselves of Muv Luv.
This happens some years after ALO - perhaps around the time where Acclitization would have happened instead. I wonder how much more different the Muv Luv plot would be if Kirito and Asuna were the main couples.
The second crossover idea is a potentially more disturbing one, also set at the same time.
A Lolipop Chainsaw Crossover.
Asuna wakes up in Julia Scarlet's body, in a VR Version of the Lollipop Chainsaw game. Kirito wakes up in Nick's body. Can Kirito avoid Zombification? How would both of them react to Sensei? If Kirito is zombified, what if the game hijacks Asuna's body, and forces her avatar to behead Kirito and put him in the same position as Nick was for the entire game? What would both of them think of the entire game?
This is partly inspired by the costumes add ons for Lollipop Chainsaw, where avatars from other animes like Kore Wa Zombie or High School of the Dead replaced the default avatar.
Edit: My bad about mixing the names up. One error seemed to have led to a huge chain of errors.