There is no rumor of a 15" MBA, just scottsdale saying he wishes there would be one.
That is NOT true. I would buy a 15" MBA, but it would be my "desktop" MBA. I would still use a 13" MBA as my PRIMARY MAC. Providing the rev C gives us the updates. I think there will be a 15" Mac notebook that has a similar form factor to the current MBA only larger display. If one thinks about it, it would be really easy to make a more powerful 3.5 lbs MacBook Air with a 15" display, which would probably even accept a 2.5" drive. It would really only be about 3/4 of an inch wider and would get rid of some of the terrible bezel.
A 15" MacBook with an AIR form thin case would make a world of sense. The whole 13" is consumer, and 15" is Pro thing is ridiculous. Pros want smaller, and consumers want bigger, too.
Also, there is/was a very solid rumor about a 15" MBA coming out Summer 2009. Apparently the rumor came from someone inside to an analyst. Also, there is another rumor that the MB aluminum unibody case will end up becoming a MacBook Pro. Another rumor says the Air form factor will become the MB. And that makes a world of sense, especially if you add a 15" MB that has a thin case too.
So, Pro equals dedicated graphics and blu ray (possibly - some form of optical drive). Consumer MB equals GPU and no optical drive to make for the cost differences.
If one thinks about the price of components of the MBA vs MB, the MBA cannot cost much more to make (smaller drive form equals less space not more cost), displays are similar now, and other components are all similar in price. So, Apple could sell a rev C MBA as a MacBook for a base price of around $1399, then offer a world of BTO or hard configured options catering to much more people than the MB currently does. Us MBA fans would pay the extra for SSD, OLED display, and etc. Imagine us use to paying for the MBA.
$1399
+ $500 OLED Display
+ $700 256 GB SSD
+ $800 8 GB RAM
+ $200 6-hour smart battery (add 1/2 lb if we WANT)
+ $200 dock station
+ $99 AT&T 3G card
+ would would pay for lots of other things.
I don't care what it's called, I want an Air form factor and a bunch of options to upgrade. This could allow Apple to sell the heck out of the MB for base price - I would think they could sell 20 million of them in the first year offered if they included an external optical drive at $1399!!!
The tech is here to provide it as a 2.13 GHz SL9600, 8GB RAM, maybe 256 GB SSD, and battery tech. For the 15" version, a standard voltage CPU would easily be cooled (unless came up with liquid cooling for 13"). So, figure a 2.4 GHz CPU standard with upgrade possibilities to higher powered 2.66 or 2.93 even... 15" would give for some cooling space.
Think up some other things that would inspire 20 million different buyers to buy one model MacBook with current rev B MBA form factor, but with a ton of BTO options to cater to low end MB and high end MBA target markets.
I really think Apple should quit trying to make one or two models that fit all. What we REALLY WANT is BTO options to make the Mac we all want. Look at a Dell order with all of the options. Three CPU options, four RAM options, battery options, four drive options, and etc etc etc. That model allows for a low starting price yet allows high end buyers to get everything they want from the same model.
I just think a MB could sell so many more with two sized displays, an MBA form factor, and a world of BTO options. Everyone gets happy. Apple sells more and can keep margins up too!