I don't believe that's effective, especially for projects like Net::SSH and Capistrano where the hacker-to-user ratio is so low. If someone wants to step forward and maintain Capistrano, they'll do so, and the community will organize around them because they'll show they have the passion to do it. If no one steps forward, then an appointment would have failed anyway, because obviously no one has the necessary passion to maintain it, and it might be better for it to die and make way for other alternatives. Either way, appointing a successor would be futile.
Even if no one steps forward, would that be so bad? Capistrano works perfectly well for the vast majority of folks. It's not like I'm leaving behind a legacy of mostly-broken software. :)