Afilias doesn't use it; wouldn't mind diminishing the code base by its removal.
There appear to be some users of it that would be injured by its removal, so that seems like a no-go.
An attractive idea: Split slon into two forms:
1. The "usual" one which manages nodes that are databases amenable to forwarding, failover, and such
2. Log-shipping-only nodes
Note that there is a lot of log-shipping functionality strewn throughout remote_worker.c. If split out, this might make the log shipping node code simple, and regular slon simpler, too.