Don't get me wrong, I would love to see him there and agree with some people on here that it would be somewhat of an epic coming back appearance.
Now now, Phil wasn't the guy who decided what Apple would and would not have ready to introduce at the expo.

And besides, Phil has been helping out in Steve's keynotes for years and years. Just look through some of the Macworld and WWDC keynotes up on YouTube.
Edit: I just noticed the bold in your quote and realized you were talking specifically about the comeback part. However, it'd be just as cool in my mind if Steve strolled on-stage as they were hanging up. Rock-star-esque cheers from the crowd, etc. It'd be sort of like easing us back from Steveless keynotes into Steve running the show again.
What would be cool is if it went like this.
Announcer: Now to present the keynote, I give you Phil Schiller!
Crowd: .........
Steve Jobs: *Walks on stage*
Crowd: Huge applause and roar for ten minutes!
OR
Announcer: Now to present the keynote, I give you Phil Schiller!
Phil Schiller: *Walks on stage* "Thank you all for joining us. We are excited to see many developers and peers come out in praise of iPhone OS and Mac OS X. Now I but some of you are wondering what I meant by "us" and "we." Let me elaborate for you. I now present to you the CEO of Apple. inc! Mr. Steve Jobs everyone!!!"
Steve Jobs: *Walks on stage*
Crowd: Huge applause and roar for ten minutes!
Steve Jobs: "Thank you! Thank you! Now onto my health! I am fine. I'm not going to die. I will remain with your as CEO and a part of Apple for as long as I live. I am very exited to have Phil
and I talk to you about iPhone OS 3.0, Mac OS X Snow Leopard, Mac OS X Snow Leopard Server, and [insert insanely cool new Apple gadget here; such as the xMac, Apple Tablet, or Apple netbook]."
I prefer the second situation. Except I would like the [insert insanely cool new Apple gadget here; such as the xMac, Apple Tablet, or Apple netbook] to not be announced until last and in the mean time they can refer to it as "something special."
Btw, I almost cried while typing up this post..
