I disagree, I think the next phone will be a major improvement. The iphone has pretty much stood still whilst android have caught up. The 3G was basically what the 3G should have been and at the time was sufficient because there was nothing else to rival it. this is no longer the case with some of the android offerings so Apple now have to raise their game.
What are you basing this on?
When has apple ever offered the best product?
They will make a small alteration as they do not want to allienate other customer, plus they will want to continue selling the 3g and 3gs so the new one will be a small improvement, it will look the same, so the match the ipad, and will be just a small improvement. The biggest change may well be the software update to 4.0 but the hardware will continue apples tradition of small increases.
Its not like they are currently losing out to android, nor are they likely in the future, as they have an item that sells and that performs tasks that everyone wants.
I would bet good money that the only improvements will be in battery and processor speed, with a new innovation that no one wants but enough plebs will trade in their 3gs's for. They may also change the screen slightly.
But again, whats the need if the current item does what the consumer wants, to make a massive improvement, and give away to competitors their ideas.
They will only make massive updates when they need to, and right now, they have no reason to be worried at all.