I disagree. Upgrades are never that dramatic from previous version.
IMO, the processor/ram stays roughly the same (as iphone 3gs) performance wise while they try to tweak better battery life.
OLED screen. Higher resolution. Better camera/hd recording. Storage bump. These alone will have apple fanboys foaming at the mouth.
Tweak to form factor because it needs to look different this time.
Main theme of 4.0 will be multitasking & notifications for this and iphone 3gs. The first couple of iphones (original and 3G) will probably be too slow to handle it. Apple has to be careful here as to not make this too complex for the average iphone user.
Still think too soon for LTE/4G version, but never know.
There are new processors coming out clocking at 1Ghz from Samsung which is Apple's supplier for iPhone processors that actually consumes LESS battery, so they don't need to stop making it faster to save the battery.
Apple has been stubborn on OLED, I highly doubt it will happen. Got that blu-ray in your iMac yet?
It's definitely going to look different this time but I don't see a change in the form factor. I see it still being a slab but this time it will be a different texture. I can see apple making a plastic that is identical to aluminum in look and feel but is fully plastic so that the radios don't have trouble getting through it.
The point you brought up about OS 4.0 is very interesting! If they made it advanced enough, they could do a "Boom!" and announce it for both the iPhone as a revolutionary mobile OS, and for the iTablet (TBA) as a desktop OS if it's really similar enough to Snow Leopard. (Steve: "a mobile OS, a desktop OS, and an iPod OS... repeat x3.. are you getting it? It's all one OS!") I believe Snow Leopard has an altered Kernel and the current iPhone OS is based on OS X Leopard's Kernel soo.. An updated kernel for iPhone OS 4.0 is to be expected as well.
As for 4G/LTE.. They could implement the radios secretly so that when 4G networks are up it can take advantage of them. Knowing apple they wouldn't tell anyone (like they did for iPod touch 2nd gen with Bluetooth chips) until the next year and then everyone would **** start crapping apples with excitement.