Hey, yea, you really hit the nail on the head. This thread was made for me to gauge "customer sentiment" towards the idea, as I worked on it more, since this forum is full of tech loving people :)
Personally, I would love something like this, I've searched for customize-able laptops but they were always about me customizing the specs, not so much about me being able to swap out parts. And they were really costly to boot.
What I'm going for is something that could be reused like in a desktop PC (I normally reuse the PSU, case, storage drives, and i think most people do the same, mainly upgrading CPU, mobo, ram, GPU), so I felt the "chassis" surrounding the SBC would be analogous to the PSU, case and storage drives that ordinarily last far longer than the 'core' of the system. So that's essentially the value proposition, allowing people to have the option to really upgrade their laptops as time goes on, rather than just adding a stick of ram or increasing the size of the drives.
And yea I definitely agree that SBCs are relatively under-powered now compared to chip coming from Intel and AMD, but I think that they are definitely crossing into the threshold where people can do work with them. Raspberry Pi 4s getting an 8Gb version, and the AMD V1000 are (I hope) a sign of things to come.
In my current design, I designed a slotted rail system, that allows 2 mounting nuts to be moved to any location within the 12cm*6cm space, so the SBCs can be mounted via the mounting holes. After I draw the CAD I'll attach some screenshots so that it's clearer. As for the ports, I'm trying to utilize ports that are the most common, based off SBC DBs databases.
Thanks for the comment man, I had a good time thinking through the points you raised.