It sure is a possibility, though less likely I'd have thought as it really would be awful publicity for Arriva/DB» if they were to do the same thing twice, and the two Grand Central routes have much more potential.
Don't think the locals around Arriva head office in Sunderland would be too happy if their London link were to be removed, plus the directors now have a free first class direct service to their meetings in London. (Not that I'm a cynic)