[distcs]

Are there no other people who can work on the TeX and Metafont after Knuth? What if someone else wants to create bug fixes for these projects? How would they version TeX? Or do they have to fork TeX and have a new versioning system?

[Rygian]

Straight from Knuth's paper: "anybody can make use of my programs in whatever way they wish, as long as they do not use the names TeX, METAFONT, or Computer Modern. In particular, any person or group who wants to produce a program superior to mine is free to do so. However, nobody is allowed to call a system TeX or METAFONT unless that system conforms 100% to my own programs."

https://tug.org/TUGboat/Articles/tb11-4/tb30knut.pdf