SDI won't disappear overnight, so there's no need to be worried about it. Even if all work on it is halted, SDI would continue to work for years to come but without updated driverpacks its usefulness would be diminished.
The project was created by PC technicians and we shared it with the community because it didn't cost us and we were happy to help others. The project grew to become very demanding for project maintainers, especially considering its weekly updates. I wish more people would join the project as contributors, so that each contributor would have fewer responsibilities and wouldn't have to dedicate as much time.
As for me, I plan to eventually leave the project(or take the position of technical consultant) but I can't do that till I transfer all of my responsibilities to other people.