Just a data point in the conversation.
The last time I added Amano shrimp to my tank was in 2003, and those had been alive for at leaset a year if not more. Today, on the cusp of 2013 I count three shrimp easily spotted feeding on the biofilm.
My tank is freashwater only, and per my understanding NOT condusive to breeding the species.
So by my reconing, 10+ years can be achived with good conditions.