Dan has confirmed on flickr here that most of the Northumberland County Council contracts (at least those with GNE) expire 3rd April. This was in direct relation to the 434/448 but likely also includes the Hexham locals. As far as other operators, there'll presumably be the Wooler services, X14 Morpeth to Thropton, 418, and 58 coming up for renewal, along with the many one day a week/one journey a day rural services.