I don't see Jobs showing up. His presence will only serve to undermine Cook and overshadow the announcement.
I think that Jobs might be there in the background unseen for support and that Cook might take it upon himself to alter the script and request that Jobs come up to the stage and everyone give him an ovation for all the work he has done. But it won't be in the script for Jobs to do anything with the keynote.
Also, that whole 'comfort of his home' is bunk. If Jobs was that sick he wouldn't have asked to be made Chairman or gotten the post. And no way would Cook or anyone else say anything about Jobs health because now there really isn't any legal reason they have to making such comments 100% a privacy invasion. Not to mention that the company is still in the throes of the whole "Steve Jobs is Apple. When he is gone the company is over" nonsense. If they were going to say anything they would do a surprise FaceTime hook up with Steve in his office on campus just to affirm that he's not in the hospital wheezing out his last breath
Steve, Stay at home and get well.
rather erroneous statement on two levels
1. We have no proof he's under the weather at the moment so there could be no reason for him to be at home or hospital which is why he is at neither
2. the man had pancreatic cancer and a liver transplant. You never 'get well' after such things. Either of them mucks with the basic body chemistry to the point that a person has hormone issues for life, particularly related to weight and muscle mass. You will always look a half step from kicking the bucket even when you are fine. And that's just with one. With both conditions, you really will never 'get well' or look well. But you could be in excellent health for someone that had either condition and good health for a general person. And live another 40 years while all the naysayers drop dead in 10 from too much fried food or get hit by a bus next week.
If Jobs doesn't show there will be no proof that there is an issue with his health, although the blogs will gather hits by claiming in fact that is the reason. He could just be staying away so he doesn't upstage the company CEO. And to continue his campaign to show the world that he is not Apple. There are other folks in the company who are smart, creative etc.