I'd focus more of the business and professional end rather than catering to all groups. I'd also focus on reduce and reuse for the components. Also sell more for the repair facilities to leverage.
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I'd simplify the product line, there should only be
T-series (for professional work)
X-series (for travelling work)
G-series (for gaming)
The X-series I would make as thin and portable as possible, but sacrifice customizability. i.e. no user replaceable parts. This would also be the cheapest in the line and the least repairable so it can be given out to operational employees and have it more or less disposable. I'd also set up a program with businesses to allow lease/recycling on this series because the shell could technically be reused and the internal board be swapped. The X would be the only one which can be folded back to become a tablet.
The T-series I would make as thin and portable as possible, but not sacrifice customizability. basically everything down to the processor is user replaceable. In order to save costs and engineering I would not bother with discrete graphics option. Since this would be more designed for professional work rather than gaming/graphics. The T's are also user replaceable screens so that 3rd party can swap it with a 4K display which we will do telemetry to check the general adoption. Also to save on cost and engineering and reuse the T's won't support tablet mode..
The X and T series would also be limited to 1080p FHD displays again to save on cost.
The G-series would be a different beast in that it's meant as a gaming grade device and the general bulk associated with it. It only comes in 17" 4K display screen with NVidia (or AMD exclusive whichever one gives us a better deal) option. Weighs like a tonne (well 6lbs). Also the G will not be foldable for engineering reasons.
I'd also add a G-dock which is a USB-C pluggable device that provides a graphics card slot that would allow offloading graphics workloads to it along with providing extra storage. This allows the X and T series to avail of discrete graphics.
Doing all of this the T and G series shells should be reusable for multiple generations. The shell structures could also be licensed at a relatively low cost so it can be 3D printed by 3rd parties with fancier materials since the company will only make stock matte black (glossy makes it easy to show dirt and grime and scratches)
Since there's **reuse** or minor iterations, costs would be lower and more beneficial for the environment than Apple's recycling approach. There's a reason why Recycle is last in Reduce-Reuse-Recycle. In fact this would be one of the selling point.
The minor iterations like updating to support new ports would simply swap the output of the shell.