If Steve Jobs shows up, he'll either be in a wheelchair or have to be helped out on stage and nobody wants that. If you've seen any of the recent photos of him, you'd know this is a non-issue - he doesn't have the strengh. If he makes an appearance at all, it will be a live video feed from his living room where he's resting in a chair. He would then announce the keynote and hand it off to Tim Cook.
People need to move on from the Steve Jobs - savior complex and let Apple move forward.
Yeah those pictures were in the tabloids so they must be true and are never photo-shopped!