COM & Nano Com carrier board design

[guimtl]

I work in industrial computer for a about 15 years now (more computer before but now focus on industrial stuff, fanless, rugged,...

I always wanted to have my own design chassis/enclosure and ports placement. made a few project using Hammond cases and pico itx boards.
Since I've made good friends at places where I have access to very decent boards and tech support in major Asian company I started thinking....

Curious what you guys think about making a COM or nano COM carrier board for 'fun' learning to manage HDMI ports, USB, high frequency traces, power supply.. it's like making your own arduino but with an i7 instead   

looking around found this; https://www.picmg.org/wp-content/uploads/PICMG_COMDG_2.0-RELEASED-2013-12-061.pdf
looks very cool, it says it all.. I could start small, get video(easiest port... ), storage and usb out..

what you guys think about a COM board for sustainability, long life, a single computer could be made to last longer than 2-3 years.
you get to keep the chassis but simply remove the nano com ''hat''  off the main carrier board...
even make a pretty decent all in one chassis that can look like a imac.. but with swappable inner CPU/RAM/Chipset module...
would be nice to get a group of people working on a global response to obsolescence..

I guess I'm not the first one to think about it.. but any reason why it didn`t happened yet? anyone interested talking about it ?
I know for a commercial product price is an issue.. but for learning and making a few boards it`s still a good idea?..