I didn't quite vote for him, because I was uncertain, but Caius Cosades would actually be a pretty cool guy to see again in TESV. Seeing as how mysterious he was in TESIII, and his affiliation with the blades (which seemed to be quite central in both TESIII and IV), his appearance in a different province could be justified.
Baurus could be cool to see again, too, but there's about a 50% or higher chance that his appearance in the sequel would be non-canon.