Personally, I kinda like companies that have an “open source contract” with a fixed date (although such could use better enforcement).
Have a period of time when the product source is closed, and get money for it. After a certain amount of money or time, release the source to the product. Then move on to something new, rinse, and repeat.
I built a small set of scripts to decrypt when the initrd starts and can load from a file in the initrd (from separate volume), EFI, or various combinations of passphrase in GRUB. The main intent isn’t to keep out somebody with physical access to the machine and sufficient time but rather makes it a lot easier to make the data unrecoverable when the drive is disposed of.
Needs more bagpipe!