Board Thread:General Discussion/@comment-25714246-20150126174816/@comment-6697950-20150813114055

Even if it wasn't removed, it's not something that activates on its own. Kayaba did not appear on the Net randomly, he performed a high-density scan of his brain, after logging out, to do it (which also led to the death of his body). I believe the doctors would have noticed if the machine did something like that on its own. And Kayaba wasn't on deathbed when he performed the scan, so there's no reason to believe that the machine is programmed to do anything special when its user dies. So, unless Cardinal decided to make more ghosts, it's highly unlikely to see Yuuki being brought back to life.