(guy was the Global Head of 3G Business Consultancy for Nokia with a background in econometric modelling division as part of that = knows what he's talking about)
Mine is just what I think Apple needs to do with upcoming revisions in a little more hardware detail. Frankly the reports are that the keyboard is fine for writing, even fast, so I don't see a physical keyboard model. However I'm forced to agree with my linky up there that removable battery/memory will become an issueI'm just not sure Apple will realize this.
Without further ado, the timeline I made up based on a) public Apple comments about when iPhone gets where, b) my linky above, and c) the hardware baseline in each market at that time.
Xmas 2007 Revision B/Europe, World
Europe's 3G iPhone (can also be sold in world outside of Japan/South Korea, NA). Main difference is 2100 MHz UMTS band, possibly GPS and/or digital TV, better camera, memory bump, video calls, oh and recording video if that hasn't been firmware enabled by then. Removable battery/memory are a possibility, and would help them sell.
Macworld 2008 Revision B/North America
North America's 3G iPhone. Main feature is 850/1900 MHz UMTS, otherwise same features as Rev B/Europe.
-SDK should be out by then if they plan on making one.
Spring 2008 Revision B/Japan, South Korea
Japanese/South Korean model because of market specific features required. UMTS 2100 MHz, GPS, one-seg TV (and SK digital TV), better camera over Europe/NA Rev B, near field contact chip for e-cash, thumbprint or retinal scanner, better (OLED) screen, other market required features. Removable battery/memory are basically required.
-Remember Japan is half the size of the USA, and way more mobile mad. It's worth it to put in Japan specific hardware. Same with South Korea (well, less population).
Tri-band UMTS iPhone with digital TV chips mature enough for multi-band. GPS for sure if it wasn't earlier, better camera yet again, WiFi 'n' and possibly WiFi 'Max', near field contact chip for e-cash (spread outside Japan by then), another memory bump, and market specific features have been reduced to software only. Removable battery/memory are likely if it hasn't happened yet.
-This allows Apple to release a single worldwide iPhone 2 with all the lessons of Revision B various iterations.
 I imagine the iPhone will not see more then modest price reductions if any for some time. I'd bet on an iPhone nano at Macworld 2009dump WiFi, lose .5" on the screen, no GPS, lower memory, worse camera, etc