The OUYA did not have this problem. They packed stock standard android hardware in to a box. The problem was that it didn't have enough games to make it worth buying or enough developers to make it work targeting.
I haven't read the details of this specific laptop in the OP but I have seen similar projects go nowhere. What usually happens is the product ends up a lot more expensive and lower quality than a mass produced laptop and the project doesn't live long enough to release a second gen of hardware.
It would make more sense for me to buy 2 Dell XPS laptops over the next 10 years that to buy this hobby project and if I even can, buy the upgrade kit.
Yeah it depends if you really can use cheap hardware with it or if they're just locking you into their own proprietary stuff, which as you say, could just get discontinued.
There isn’t a huge amount of ready to use phone hardware from multiple competitive consumer suppliers I feel like integrating into a phone myself.
But there are those things for a laptop.
If they can make this work at a reasonable price it would be appealing even to me as an ardent Mac user.