Gaming: Fair point. However, with next generation consoles overtaking PCs and portable gaming devices surely to follow that mold, it's doubtful PC laptops will play any significant role in that for very long either. If the demand for PC games drops because of new consoles, you'll run into similar issues than the mac is faced now.
Upgradability: mmh. how many people actually upgrade processors in laptops? Seems to me that this is a pretty daunting tasks at least for most brand-name laptops. Remember, we are talking laptops here, it's a very valid point when it comes to desktops.
Availability of software (non-gaming): Ok, this one is just wrong. believe me, i held that to be true for a long long time myself. But it's one of these persistent myths. For every program on the pc side, there's a better equivalent for OS X. Don't believe me, challenge me. Name me an app you are using and i'll find you a great equivalent (Note: i'm not talking about legacy stuff here, eg. if your company wrote an intranet service that works only on IE/Win, yeah then you're screwed...but that's a different issue altogether). What's more, due to Apple's strict, well thought-out UI and programming guidelines, OS X native 3rd party apps often tend to be more functional, coherent, consistent and much better integrated than their win counterparts. Thus, there's also a much greater availability of quality
(stress: quality) freeware and little apps (under $30).
OS X: well, it's pointless to argue about it, i know, because people are so settled in their opinions, but if you have ever used OS X Tiger, you know how much more functional, efficient, well-designed, and feature-laden it is when compared to XP. In terms of usability there's just no contest. The os x interface is much more responsive and polished than KDM or Gnome (not to say that this cannot change); and if your roaming the command line, well, there's no difference to any other *nix installation. (let's not forget we're talking solid BSD underpinnings here).
Price: price points are expected to be much lower for the new mactel machines. it remains to be seen, however, how much lower. But even assuming mactel machines with today's price points, if you factor in the quality of parts and the pre-installed installation packages (the iLife apps, iWork etc.) there isn't that much of a difference. will it beat the cost of a white-box running Slackware? hell, no! but that's apples to oranges really. (hey, i love compiling my own drivers too, but that's an hobby not everybody shares!).
Screen: resolution on ibooks, yes, apple has been to slow to adopt hi-res screens on the ibook. no doubt in my mind that new ibooks will come with at least WXGA+ screens. In terms of brightness and color reproduction, however, apple's laptop screens have always been top of the line.
So, wow, that turned into a rant quickly.
But since everybody here is looking for a great laptop for what it's worth, why not keep an open mind about it too. It always makes sense to revisit some of your old prejudices to check if they still hold true...