I don't see a point for 14.1" size unless they can really make it fit in the current 13.3" chassis and I doubt they can't.
From seeing other manufacturers notebooks there is usually considerable chassis size difference between 13.3" vs 14".
I have Asus Zenbook 14" and it is much larger than my MBA or MBP 13.3" was.
So why increase the size of the smaller one and make it less portable friendly? I think those who want bigger and less portable machine will go with the 16" anyway. That's what I would do if I wanted bigger than 13.3" which in my opinion is the perfect compromise.
I disagree, but each to their own reasoning. I think the way that the laptop market and technology is shifting, reducing the bezel size is inevitable. Maybe not Dell XPS size, but a reduction for sure. It goes in line with contemporary design, such as seen on phones, TVs and interfaces.
I also think with them expanding the 15.4" to 16", the transition from 13.3" to 14" is inevitable. It just seems nice, clean and "Apple". The 13.3" is 1.4kg at the moment, so even if they didn't go full-XPS on the bezels, it'll still be south of 1.5kg I imagine, which gives it breathing room between that and the 2.0kg 16" MBP.
I think with the Pro machines, the smaller Pro is the "portable Pro", and the large Pro is the "Desk Pro". Yes, as you say there will be people in the small-Pro market who won't appreciate any extra weight whatsoever. But, there will also be a large number I imagine who will appreciate a little more screen real estate for a fraction extra weight. It's not the case of "Right, I might as well go full-Pro and get the 16-inch", there's a world of weight difference between 1.4kg (or a little extra, if they increase the weight slightly) and 2.0kg. I think that they'd both still be nicely in different camps.
And that'd allow for a 12.5"-13" MBA. They might marry the exact same screen from the 12.9" iPad Pro, to streamline their supply line (I'm not a tech guru, so if that doesn't make sense, apologies). If the lets-say-12.9in-MBA was in the same (or just slightly larger) form factor as the 12" Macbook, I'd imagine that it'd be around 1.1kg, given that it'd be a little chunkier to allow for a proper keyboard and internals to have 2 x 40gbps Thunderbolt ports. The butterfly keyboard and single-10gbps-port are two of the "lets never go back to that" compromises that I don't Apple would take again.
Tim & Co's approach is very much of a perfect formula of innovation whilst still appealing to the masses on an industrial scale. Striking down the middle whilst still raising the bar. So, whilst they won't go back to the cavalier risk-taking of Jobs & Ive, I think the fact of the "Air" barely distinguishing itself from the Pro (7.9% lighter, c'mon!) will be an itch that they need to scratch. Personally, I think they're busting to bang-on again about how ridiculously light their lightest laptop is, but any talk of lightness has to be almost tongue-in-cheek at the moment. Pushing the Air and Pro away from each other slightly would give them this sales pitch again.
All of this is speculation though, so what you're saying is just as valid as my thought-process.
