What I have wanted for years was a small little portable desktop (sort of like those intel NUC's but larger and more powerful) that was basically using laptop like internals but designed more for speed, power, and efficient cooling. You could then pair that with a decent sized external monitor (like some kind of portable 21 or 24" 16:10 widescreen - maybe even one that folds) and a small, folding mechanical keyboard (I have preferred the 87 key layout for almost a decade now for everything). On that keyboard would be a mouse knub (like Thinkpads and many business laptops) and below the spacebar would be two mouse buttons (also like a Thinkpad) so that you can click with your thumbs.
This setup would be super efficient for real mobile workstation use. I have yet to find a system more efficient than the "eraser" mouse knub - you can type and use the mouth without ever moving your hands off the keyboard or the proper row AND you can easily click the mouse with your thumbs which makes for extremely fast transitioning between typing and mouse use. Once you get used to the knub it is actually very accurate (some laptops have much better implementations of this than others) - I would say up there with the best trackpads.
You could also take advantage of any and all screens you might come across while travelling - go to a friends house and they have a nice, larger TV? That becomes your second monitor. Etc etc. And with this keyboard setup you can also even sit on a touch and not have to deal with an awkward trackpad or mouse setup.
You could accomplish the same thing with a decent laptop but you would have a lot of extra space taken up by a keyboard you may not use often and a small screen you might use but not really want to use.
Alternatively I suppose a thicker laptop could be made with this type of keyboard integrated and it could also have some type of fancy fold out screen (similar to those new Samsung phones). I don't personally care how thick my laptop is or what the obsession is with thinness - storing and transporting a laptop (for myself at least) is always limited by the other physical dimensions. I do not also really care all that much about weight - most situations in which I would be carrying one I am not going to notice a huge difference between 5 pounds and 15. Although for backpacking of course (which is pretty niche) a light laptop would be nice.