All the spoutcraft functions need to provide ways of declaring what happens if Spoutcraft was not found. A plugin might be able to hobble along just fine without spoutcraft, or it may absolutely require spoutcraft in order to keep going.

Looking at the current state of Spout and it looks like implementing this right now may be premature since they are in the process of scrapping SpoutPlugin and SpoutCraft entirely, in favour of the new Spout engine. I think I'll wait and see what happens with this project first.