if this happens, I would more like it to be like an ipod nano in form factor. say a multi touch pad where the wheel is that has numbers/letters like a normal phone. but has an overlay to show the old scroll wheel... and make it all click like their new trackpads/storm.
no 3g. no wifi. no apps. just the barebones phone and mp3/video player. I would seriously consider switching for that. or better yet, att bring out a cdma version so I don't have to, heh. the major problem with this is pricing.... you make it 8GB, and $150, you cripple your ipod nano market. to an extent anyway. maybe you make it 4GB, then have 8GB at 200. But then it pushes on iphone territory, but no forced data plan.
but given the case rumors, i hope that smaller, higher dpi iphone is not necessarily true. I'm not sure how a smaller screen will hurt. it'd hurt a lot if they couldn't get the higher dpi too.