In an optimal world, you'd pass along the project code to someone else and let it live. If there are people who are willing to run it, or use it, then we should make that happen (one of the ideas of Bitcoin are openness and accessibility).
The code can be replicated, the trust cannot be. One of the reasons that Bitmixer was so successful was that people were ready to trust it with large amounts of Bitcoin. I doubt if they will do it if new users took over.