So yeah, there's no exact answer to "what happens to Linux after Torvalds", it's more of "who gets to add more maintainers to torvalds/linux.git if nobody merges things in there for 72 hours". I suppose Linus is confident that the system of distributed maintainers is robust enough to survive his & gregkh's incapacitation, and the only remaining point of failure is access to the central repo itself. I think he is underestimating the governance upheaval that would happen if he was to disappear, so I hope that he puts some more details about his views on future project governance in writing.