Simply put, it'll be eternal slumber, permanent "Fulldive" state, coma, the likes. Without a controlling consciousness, which is the Fluctlight, Kirito's and Asuna's bodies are basically going to remain there 'on standby' forever.
...I just thought of something disturbingly fun. Who was the one who mentioned giving Alice a proper body?
Spoiler for Open at your own risk.:
Without a Fluctlight, the body becomes an empty shell until the STL machine lets the owner's Fluctlight reenter the body.
If you haven't caught on by now, let me drop the bomb: Say, Alice's Fluctlight is inserted into Asuna's body by the STL.
Let the disturbing fantasies begin!
(: