No, this isn't that hard. You could design two lines of products and satisfy almost everyone: MacBook and MacBook Pro.
The MacBook line would be optimized for mobility, for pros and college students who need a real computer (not an iToy) with them all the time to do serious work of a general businessy nature: organize projects into folders, use apps like a browser, Keynote, Excel, Word, lightweight photo apps, media viewing, a good text/code editor, a terminal, etc. Lots of reading and writing work, software dev on the road, email, checking flight status, giving presentations (in the office, in class), etc. It would be designed to have battery life extended significantly via 3rd-party USB-C batteries, so you would have the mobility of a light machine with the option of significantly extending battery life when you needed it. Lightweight, mobile, untethered, pro work.
The MacBook Pro line would be optimized for computer power that was still portable: NVidia GPU, lots of RAM, lots of internal storage, big screen (17" version available again), serious battery life, no connector shortage. The words "thinner" would never be uttered. Instead: "more powerful". By allowing it to be a little thicker and heavier (not huge, maybe 50% thicker than a 2015 MacBook Pro), you could use less compact, previous gen RAM and SSD, thereby getting much more for the same price. It wouldn't actually be very thick and heavy except relative to the lightweight line; it would just be optimized for how much of a serious computer you could deliver without making it too large, rather than the current "how thin can we make it without rendering it useless?" This machine would often be used docked to large monitors as a full-powered desktop but could be taken on the road (these things wouldn't be any larger than every laptop used on the road a few years ago.) Photoshop, 3D graphics rendering, serious gaming, video editing, serious software dev docked to large, desktop screens that could be continued on an airplane, number crunching AI and big(ish) data without having to offload to a server farm, having 100 tabs open in Chrome while editing 4K video, having a full library of books and 100 videos on the internal drive for use when traveling, etc.
These two lines could share most design and mfg yet satisfy pros of all sorts without needing much of an increase in number of models made.
Unfortunately Apple does not (well, not any more). And there is a huge contingent who still wants the thinnest possible Pro model.
I would suggest further breaking the Non-pro line into super thin (New Macbook) and thin (Macbook Air) models, and the Pro line into super thin (2016 rMBP) and not-so-thin (the model you describe).
The MacBook line would be optimized for mobility, for pros and college students who need a real computer (not an iToy) with them all the time to do serious work of a general businessy nature: organize projects into folders, use apps like a browser, Keynote, Excel, Word, lightweight photo apps, media viewing, a good text/code editor, a terminal, etc. Lots of reading and writing work, software dev on the road, email, checking flight status, giving presentations (in the office, in class), etc. It would be designed to have battery life extended significantly via 3rd-party USB-C batteries, so you would have the mobility of a light machine with the option of significantly extending battery life when you needed it. Lightweight, mobile, untethered, pro work.
The MacBook Pro line would be optimized for computer power that was still portable: NVidia GPU, lots of RAM, lots of internal storage, big screen (17" version available again), serious battery life, no connector shortage. The words "thinner" would never be uttered. Instead: "more powerful". By allowing it to be a little thicker and heavier (not huge, maybe 50% thicker than a 2015 MacBook Pro), you could use less compact, previous gen RAM and SSD, thereby getting much more for the same price. It wouldn't actually be very thick and heavy except relative to the lightweight line; it would just be optimized for how much of a serious computer you could deliver without making it too large, rather than the current "how thin can we make it without rendering it useless?" This machine would often be used docked to large monitors as a full-powered desktop but could be taken on the road (these things wouldn't be any larger than every laptop used on the road a few years ago.) Photoshop, 3D graphics rendering, serious gaming, video editing, serious software dev docked to large, desktop screens that could be continued on an airplane, number crunching AI and big(ish) data without having to offload to a server farm, having 100 tabs open in Chrome while editing 4K video, having a full library of books and 100 videos on the internal drive for use when traveling, etc.
These two lines could share most design and mfg yet satisfy pros of all sorts without needing much of an increase in number of models made.