Modern laptop buyer groups:
Group 1) Price sensitive and typically values user experience (size, weight, screen quality, kb feel, etc) over specs.
For Apple this is iPad, iPadPro, MB, MBA territory. Competition is under $500 PC laptops, other tablets, phablets...
2) Laptoppers - folks who use them for everything from email to spreadsheets to watching GOT. They need easy to live with - long battery life, easy to carry around, decent display, etc.
3) Serious tech heads and posers seeking street cred. Specs should be desktop class. Display should be 3840 pixels wide (2160 or 2400 H) with 10 bit color, >95% P3 gamut. Ultra modern casing to attract well heeled, image conscious buyers.
I submit that Apple already has plenty (perhaps too many) options for the first two groups. The underserved segment is actually the high end where $4-8K for a serious work machine is not an issue. Moreover, the traditional office setting filled with desktops is trending toward a far more mobile model where having serious computing resources in your shoulder bag or backpack can be a real asset.