The keynotes have been less and less Steveo heavy of late, and I think this was part of the plan. The real excitement has been what Apple is releasing, not what Steve Jobs has cooked up. I think they'll only need a cycle or two of really great stuff without Steve at the helm and people will stay excited.
I really doubt that all the marketing, the development, the *everything* has been Steve. He has a massive perfectionist streak, but I'd bet that just about all he is has been encapsulated and institutionalized. I don't think we'll even see Cook at keynotes because he's the wrong guy. He runs the company but is not the visionary. It's been said that he's flat out brilliant on manufacturing chain, development cycles, retail - all of the real business stuff. But with Steveo as chairman and folks like Johnny Ive still in tight, then perhaps this move will simply make it that whatever Steve has left can be more artistic than operational.
Meaning that, we will probably see him in little appearances as the sage elder - the Henry Ford, the Walt Disney that comes to the forefront now and again, rather than flying to China to cut deals. Because really, that's what the CEO does. Daily ops. And as he slowly slips from public view, others will come to light as the behind-the-curtain jeeneus that built (this product) or (that ware).
I would REALLY like to hope that Apple learned it's Scully lesson and will now be with us for good.
@ DV8R - that's right - I started with the ][ in about '77, looking at you behind the glass door and thinking, "I'll bet I can avoid Algebra if I can get in there and do what he's doing..."

You were an inspiration even then old friend.