Not necessarily. If a project doesn't merge a proposed patch, the patch could simply be deemed inappropriate for the projects chosen direction. So if a fork do

Not necessarily. If a project doesn't merge a proposed patch, the patch could simply be deemed inappropriate for the projects chosen direction. So if a fork doesn't get merged upstream, I see this as a failed fork. If a upstream stops working on their project and stops accepting patches, the outlined problems can happen, but just look at any random sourceforge project not updated since 2006. In the old days, there was practically no way for other contributors to get back on track, but it wasn't logged for eternity either - the project just died. Today, Github at least provides a chance to get back on track, but, again, your perception might be altered by the fact that on Github you don't just see the successful reboots, but also all the failed ones?