Long time watcher, first time poster here.
In view of the proposed closure of Chester-le-Street depot couldn't there possibly be a scope here for GNE to be future ready by making bigger changes now in terms of business premises and company operation rather than small changes every few years.
My thoughts are that if Chester-le-Street depot is going to be too expensive to maintain the current building then possibly look at these two solutions:-

1st - Demolish Chester-le-Street depot entirely, do the ground works as required, create a new outside parking depot on the existing site with a new engineering facility building and a few offices (not all offices needed as in previous years).. or

2nd - Give up the Chester-le-Street land entirely and build a new super depot at Follingsby Park, integrate Washington, Chester-le-Street and The Works in to one large facility central to both Washington, Gateshead and Chester-le-Street.  Easy road access to A184, A194M, A195, A1M, Leam Lane. Parts will be on hand in a central store at Follingsby for all vehicle types for each depot.