The Partner Plus systems are older, and firmware updates have stopped (Avaya has stopped with the Partner systems support), however, they will last a good long time.

The Bogen equipment is really good stuff. Again, should last a good long time, and can most likely be refurbed/cleaned/sold to a customer.

Asterix cage is probably useless, as Digium isn't going that route anymore, and parts are like hen's teeth. The ATA's can be put to use for a home PBX.