Michael McKean doesn't expect Chuck to get miraculously saved:
http://www.hollywoodreporter.com/fie...finale-1015251
He also doesn't think it's the last we've seen of Chuck, just because of the show's frequent use of flashbacks (and, in a way, the whole show is a flashback).
Considering that AMC let shows like Hell on Wheels and Turn finish their stories, I'd be very surprised if they don't let Saul play out.