I keep reading about the upcoming iPhone announcement and will now voice my own opinions of the topic.
Apple relies on Steve Jobs and innovation; right? I think if they are going to have as big an impact as the original iPhone announcement, they will have a smaller version, 4g instead of 3g all without to much design change, while bringing in an new model with a slightly different design and more colors.
This is probably more of a wish list but I will almost guarantee that it will be thinner. That's just how Apple rolls.