I agree, it makes no sense for the new MacBook and the MacBook Air to co-exist, together with a MacBook Pro.
However, we have to remember this is Tim's Apple we're dealing with. I'll give you some examples:
- The iPod Classic, survived an awful lot of years, until Apple could no longer even source the HDDs.
- The cMBP 13" still exists in the lineup, not having been updated since 2012.
- The iPad Mini lineup featured THREE generations of devices not very long ago, Mini, Mini 2, Mini 3.
- The iPad Air now coexists with the Air 2
Having said that, I don't think the Air will be leaving anytime soon. It will remain, in current or a revised form.
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Another important aspect. The MacBook sure may be the spiritual successor to the MacBook Air. However, the MacBook Air is Apple's best selling laptop of all time if I'm not mistaken, and may be the best legacy of Steve's old Apple, together with the iPhone, iPod and iPads. Had Apple wanted to, they could have released the 12" MB as a MacBook Air and discontinued previous models, but I don't think they were willing to take that risk.
The Air line-up of computers is such an established moniker. Although there much are better options by now, the average joe still prefers the MBA over the rMBP. My father got a new 13" rMBP from work. He still prefers his old MBA. My girlfriend wouldn't even consider a 13" rMBP. She loves her Air. What I am trying to say is that the MBA model has made a great number of followers during the last years. I even miss mine, even though I have a 13" rMBP I have considered selling it and going back to the Air.
As Apple say, the MacBook Air is simply "The notebook people love".
If Apple would have released the 12" MB as an Air, many of the traditional Air-buyers would probably have gotten rather disappointed with their new MacBook Air, once they found out they could no longer connect their USB-drives, or hold powerpoint presentations at work connected to large displays (they don't all know!). Apple would have risked the value of their entire "Sub-brand" of notebooks. Instead, they chose to release the 12" laptop as simply a MacBook.
In some ways, I think the 12" MB is a bit of an experiment. Apple needed to see how the market would react to a fanless laptop without ports (well...). I think the answer is that some people love it, some people hate it. Consequently, I don't think the 12" MB is selling as well as Apple had hoped (I say hoped, not expected). It's possible that the MBA still outsells it by a large margin. If that is indeed the case, it wouldn't be strange at all to see Apple release an updated MacBook Air.
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To be frank however, I think the rumored 13"/15" laptops are NOT MacBook Airs, but rather new, thinner MacBook Pro's.
I have been here long enough to realize that many rumors are true, but often pan out differently to how we interpret them. Here are once again a few examples:
- In 2012, rumors were spreading of a 15" MacBook Air. This turned out to be the 15" rMBP.
- In 2014, rumors were spreading of a 12" Retina MacBook Air. This is the new MacBook.
- In 2014, rumors suggested that the iPhone 6 would have a curved display. Only the edges of the phone were curved, not the display.
- In 2015, rumors suggested that the iPhone 6S would have a 3D display. This turned out to mean 3D Touch, which has nothing to do with 3D.
TL;DR: We don't know **** until Apple release their laptops!
