My speculation:
-64GB (already have iPod Touch in the capacity)
-OLED (Zune HD has it, seems the way to go now days, and apparently the quality is noticeably better)
Only for brightness, the colors seem to pop, but again outdoors its useless.
Samsung Omnia HD
Nokia N85
Nokia N86
and a few others use AMOLED and in outdoors (even on a cloudy day in N.A.) its hard to see and full brightness.
6. Video Camera (VGA/1.3MP). This would be great to have an iChat app built-in for video conferencing. Many business in today's economical climate have already done this in the office, I see no reason why 3rd party Cisco/Polycomm/Avaya/etc can use this for video conferencing (upscaled to HD) for important office meetings. This'll be great for Schiller, Jobs, Ive, & team to have impromptu meetings while in hotels abroad.
7. Increased Battery capacity; more frugal power consumption chipset.
8. Higher resolution (800x480)?? May not be needed at all though.
9. 720p/1080p Video output capability. m4p's to be on device and played on external LCD/TV's. Again may not be needed.
10. HSPA+ support with either 10Mbps down/2Mbps UP -or- 21Mbps Down/5Mbps UP. We will NOT see LTE on July 2010's iPhone as networks will still only be either in-house trialing or being built & tested. Verizon Wireless, Rogers Wireless, Telus Mobility, Bell Mobility, AllTel, and a few others around the globe (NTTDoCoMo incl) will not be ready for official services until LATE 2010 (December) or mid 2011.
Cheers.
There are improvements in firmware/software for iPhone OS needed, but that is for another thread.