Considering the broad range of such softwares that already exist, written by people such as Felix von Leitner, Gerrit Pape, Laurent Bercot, and so on, why do you think that Linus Torvalds is the person to write one? Or needs to write one?
There were many version controls systems before Git came along. He doesn't need to write it. But if he wants, he has the technical chops to do a damn good job of it.
* http://blog.darknedgy.net/technology/2015/09/05/0/
* http://skarnet.org/software/s6-linux-init/
* http://smarden.org/runit/runit-init.8.html
* http://www.fefe.de/minit/
* https://jdebp.eu/Softwares/nosh/guide/system-manager.html