Halvar wrote: That wasn't a subnotebook in any way, I'm sure it had 2 kg and was about 5 cm thick.
4.3 cm, let's be fair. But, yes, 2 kg.
Actually, your Contura Aero 4/25 example is from 1994, not 1997, but the ThinkPad in that photo is misleading because it's a (much larger) 600.
And, the standard for a notebook tended to be, about the footprint of a notebook, which is based on common paper sizes - US Letter and A4. (The ThinkPad 700/720, 75x, and 760 were actually almost exactly A4 size footprint at 11.7" x 8.3" (the 765 added an inch of depth to get a bigger screen in, and things got bigger from there), and the 700 was one of the models that defined the notebook computer.) Subnotebooks were smaller than notebooks, and the 701C was smaller than a notebook. I'm going to use inches here because that's what I've got in front of me, but...
ThinkPad 701C: 9.7" x 7.9" x 1.7", 4.5 lbs
Compaq Contura Aero 4/33c: 10.25" x 7.5" x 1.7", 4.2 lbs (yes, I used the color one, which is thicker and heavier, but it's the fair comparison)
Not that different, and the 701C has a smaller overall footprint (although it is a bit deeper, due to its 10.4" screen - but that was the whole point, it had the same screen as the full-size ThinkPads, with the same size keyboard, in a subnotebook form factor). If it's not a subnotebook, neither is the Contura Aero.
Edit: Looking through more recent ThinkPad specs, I decided how I'd make the retro ThinkPad. So, the ThinkPad was revolutionary for being a
notebook, as well as some other design characteristics. This means 11.7" x 8.3" footprint. The closest modern ThinkPad to that is the X200/X201, at 11.6" x 8.3", and somehow, they managed to cram a trackpad in there. So, it's a good place to start for this modern machine.
Put the best quality domes under those scissors, with THAT keyboard layout (not even the 20-series layout, although I'll allow the modern volume buttons).
Maybe consider making it .1" wider to match the classic ThinkPad footprint and make a bit more width available for a screen (not that it needs much more screen space, but if it does need more, width is the dimension it needs), and then remember the FlexView heritage that IBM began on the A30 series, and put a damn good screen on... maybe get Samsung to make some 13.3" 2560x1600 panels, that'd be a nice fit for that machine.
Oh, and as a nod to machines like the 760 and 600... upward-firing palmrest speakers. None of the weaksauce downward-firing crap that later ThinkPads got. (And it's nowhere near thick enough for 770/380-style forward-firing speakers, nor deep enough for upward-firing speakers behind the keyboard ala 75x/355/36x or A-series.)
For pointing devices... LEAVE THE DAMN TRACKPOINT ALONE. Then, that touchpad is pretty uselessly tiny, so I'd be tempted to make it a clickpad on a new model (and, yes, include one, so it can actually be sold), as a clickpad is probably more usable than that awful tiny thing. And, the X220/X230 are 8.1" deep and get a better clickpad in than the 8.3" deep X200/X201's traditional trackpad... (X240/X250 are 8.2" deep, for what it's worth.)
Rubberized coating, of course, toss a ThinkLight in too. Not sure how to make the homage to the RGB logo, but sure as hell not how this Lenovo concept did it.
Now, for the specs... there's a few ways to go with this. Could make it
really thin (like X250 thin), and put a 15 W ULV part in, they're pretty fast. But, to be honest, I don't like that idea. It'd be adequate, but this would kinda be a flagship, and that calls for more than "adequate". Keep it X201 thickness, maybe a bit thinner, and you could probably get enough cooling in there to run a 47 W part easily (given the business laptops I've seen cooling a 37 W CPU and a discrete GPU in less thickness...) - while I wouldn't recommend Broadwell-H, given its short lifespan, a Skylake-H would be extremely interesting.
I would probably buy the crap out of that machine (whether it's Lenovo that makes it, or my employer (but the last machine my employer made with a pointing stick in a form factor resembling this was, well, Merom and i945), or someone else) even though it doesn't really fit into my usage model that well. (Well, Steam in-home streaming and a desktop would honestly take care of a lot of it... Hmm...)