Since I like the OSR stuff I would use PE in a First or Original DnD rules format. I can definitely imagine using maps from Eternity in an ongoing campaign. Maybe have something similar to the first World of Greyhawk folio that was put out. You know, just a basic outline of the areas and controlling factions with some gorgeous maps to back it up?
What concerns me the most is the content that would be made available. Would there be spoilers for the Eternity CRPG? What would be different from the main story in the CRPG? An alternate Eternity Universe perhaps? What type of canon material would be included or discarded? Lots of questions to think about. I think it may be easier converting from a PnP game to a CRPG game than the reverse.
Maybe story lines and fragments from the CRPG that aren't entirely fleshed out can be used to create scenarios for an Eternity PnP game. That way users can get some satisfaction that they are contributing and putting their own mark on the Eternity universe in a way. But of course the main question is: Would it be profitable to release maps and fluff material for generic RPG rules?
