CIG are planning on replacing stretch goals with more in
depth design posts about different aspects of the game
the most recent one was for MobiGlas
https://robertsspaceindustries.com/comm-link/transmission/14466-Design-MobiGlas

you can see the older design posts in the "The vision becoming reality" on the status page
https://robertsspaceindustries.com/project-status
(I would also expect all of the new design posts to be linked in the status page in the future)