Might be kind of cool to make up a newly blighted island somewhere, where folks could kill off the undead (who don't then come back) and then maybe use purified essence orbs and who knows what, to 'cleanse' the blighted land and return it to a nice resourceful isle.
It would be a flow along the storyline that we can take back the land without disturbing the main blighted areas. Could run them hither and yon every year or so, so that new folks and others who missed it could have a go at it.
Not sure how hard that would be to do.
Something to think about...