ZDNet has hits and misses with their posts, particularly about Apple. In this post, I generally consider it a good post because, while I don't agree with most of it, it's a good analysis of why Apple would release a high end iPhone as well as a mid-range one with different colors.
It's worth a read to get at what Apple is planning.
For the most part, Apple doesn't play defense. It play offense whether it releases a new revolutionary product and moves into a new market, improves on existing ones, or when it allow one of its products to cannibalize another as the iPad is doing to Macs - just as long as it is taking up PC share as well.
Even with the iTunes ecosystem, Apple continues to add new contents while it works on improving its hobby, the Apple TV.
The thing is you cannot take each product unto itself and focus on it. You have to sit back and see the various pieces within Apple's mobile strategy and how to work to expand Apple's size of the market.
There is one segment in the post regarding dumb phones and how Apple will try to capture that big part of the cell phone market with the iPhone Colors. I just want to expand on that a bit. Apple is not just after anyone else who have not bought a smartphone just yet. In fact, I wager that while Apple would like anyone who has never own a modern mobile device like the iPhone or an Android device, Apple's color iPhones are also meant to be an assault on the rest of the smartphone market as well - those who bought into the cheaper lower spec Android or Windows Phone segments of the market, those who are looking to the iPhone.
As far as momentum of the iPhone, I'm not worried about that at all. Apple continues to expand iPhone sales and chip away at the rest of the mobile market a few percentage at a time. The color iPhones will only serve to hasten Apple's expanding market share.
Then again, it's not so much that that market share is important to Apple as it gains the right customer base who can appreciate its ecosystem and capture as much of the mobile profits as it can. So, while iPhone Color will be the newest Apple mobile device, it will still be only one of the many moving parts of Apple's mobile philosophy.