I missed this post before but I think you might be right. After more research, I think the MBP 17 was dropped because they could not make a retina version. The highest resolution I have seen on a 17 inch display has been 1920x1080. QHD has only made it to the 15 inch laptops, no 17 inch I have ever seen. The rMB will be 16:10, makes sense we will also see a 16:10 14 inch rMBP and a 16 inch could be doable as well.
MacBook 12": Streamlined, MacBook Air-esque vision of computing. Thin. Light. Affordable. Yet powerful (screen-wise). Integrated Iris graphics (2016 update) to support such a screen, with a Skylake processor.
MacBook Pro 14": The definitive MacBook. Performance. Light. Fantastic Retina-class screen. Portable yet powerful. In a smaller, lighter, thinner body, yet retaining the 15" screen in a 14" form factor (much like how the 12" is like the 13"). nVidia Maxwell-class: 970M. Upgraded cooling mechanism to support this new graphics card. All day battery life (Browsing, common usages.).
MacBook Pro 16": 4K screen. The previous cMBP 15"/rMBP 15" size (in terms of hardware size). nVidia Maxwell-class: 980M.
Following the desktop Macintosh distinction: Mac Mini. iMac. Mac Pro. MacBook. MacBook Pro. MacBook X.
*Keynote, 2016*
A TV-class portable device. A world-class laptop. And a breakthrough media workstation.
A TV. A laptop. And a media workstation.
A TV. A laptop. ...
Are you getting it? (YouTube link)
These are not separate devices. This is one device. And we are calling it... MacBook X.
Today, today, Apple is going to reinvent, the laptop. And here it is. *Cue Chromebook Pixel*. No, actually here it is, but we're going to leave it here for now.