I find this comment ridiculous. I don't think anyone, including Apple is worrying about the iPhone cannibalizing Laptop sales. A Laptop and Cell Phone (even the iPhone) are complementary. People will buy both, not one or the other.
The iPhone is capable of doing quick mobile browsing while you are standing in line or at a bar, but there's no way it replaces anyones laptop in its entirety.
> A Laptop and Cell Phone (even the iPhone) are complementary.
Not for much longer. Have you noticed that the most capable phones are getting larger and the least capable laptops are getting smaller. And both are available with Windows, Linux and MacOS X. See http://news.ycombinator.com/item?id=186508 a possible future mix.
Apart from the difference in usage commented above you do not worry about cannibalizing a market where you have less than 10% market share.
If you as an example could cannibalise the Laptop market by 100 units and you had 10% share of same you would only loose 10 unit sales in the first market and gain 100 units in the other market. In this case smart phones. Assume a 3 to 1 price ratio you would gain $2 for every 1$ you lost.
True competition will come from a company with no such issue to worry about.