The creator of systemd (Lennart Poettering) has recently created a new company dedicated to bringing hardware attestation to open source software.
What might this entail? A previous blog post could provide some clues:
So, let’s see how I would build a desktop OS. The trust chain matters, from the boot loader all the way to the apps. This means all code that is run must be cryptographically validated before it is run. This is in fact where big distributions currently fail pretty badly. This is a fault of current Linux distributions though, not of SecureBoot in general.
If this technology is successful, the end result could be that we would see our Linux laptops one day being as locked down as an Iphone or Android device.
There are lots of others who are equally concerned about this possibility: https://news.ycombinator.com/item?id=46784572
I have seen some platforms locked to Microsoft first party keys only. They boiled the frog by starting with it being optional, able to enroll your own keys, and Microsoft signing third party bootloaders, but now there exists a Microsoft-only certificate regime that at least some vendors have selected, or at least made a selectable option. The pitch being that Windows shops that don’t trust their users can be assured they aren’t deviating from the blessed windows os their IT trusts.