Very nice post, and I completely agree with your points.
It will be extremely disappointing to see just an iPhone 4S this year after everything we've been seeing so far.
Do you think there will be two new iPhones? Or 1 new iPhone and 1 internally upgraded one?
I have no idea.
Before with the iPod touches, Apple would keep the old generation as the low end option. When they introduced the fourth generation one last year, they totally upgraded them all, even the low end option. This is because they wanted facetime to be in the hands of more people, and that is why all touch models were updated.
With the iPhone, I think they are more likely to have an iPhone 5 and a "4S" if you want to call. I don't think we should get stuck with specific names just yet. I think that after all this time, having an iPhone 4S and a 4 would be a bad move on Apple's part. I think it was a bad move with the 3GS and 3G.
Back then, the phone market was totally different. Apple has much more competition now, and people were getting confused with 3G not meaning third generation. Now, the numbers line up, completely. A5, iOS 5, 5th generation iPhone. With all the 5's, I don't think Apple will only show a 4S, but that is only speculation on the NAME, not the design.
I am using a 3GS right now and it is painfully slow. No matter what comes out, it will be a big upgrade. Even a 3GS to a 4 would have been a big upgrade. Upgrading to a dual-core A5, 8MP (possibly backlit) sensor, and the "Assistant" feature will be incredible.
I also think people have made good points about Cook's first big announcement not being a simple spec bump. But generally they don't use their own campus for a big upgrade.
What's your theory on what will happen?