Some of the changes have started appearing in the journey planning section of the Arriva app/website. Had a quick play around with some of the bits in Durham and Darlington and these were some observations not previously mentioned (assuming info is correct, current times still show in some instances):
3/3A - becomes Town Centre to Skerne Park only as service 3, except for extensions to/from Hummersknot Academy on school days at start/finish times.
19 - West Park no longer served, instead running in a one way loop of Faverdale via West Auckland Road then turning right at the roundabout onto Rotary Way then as current route.
X75/X76 - X76 withdrawn, X75 running hourly with a few extras at peak times.
Beyond changes we already know, like 1 being diverted via Tindle Crescent, it's mostly changes to times.
Arriva North East: Upcoming Service Changes