This is what I think may happen:

5275 - 5279 for 12/12A, likely to become "Blaydon Racers" as this is a relevant brand to the route  branded which would lead to 5234 - 5238 becoming free.

I think 5234 - 5238 might head back up to Stanley firstly for standardisation. I think if they head up to Stanley, Toon Link livery will be kept however route description for services X70/X71 with excluding the 6 this has a PVR of 4. The 5th OmniCity, 5238 could become a "Toon Link Spare" for example, still carrying the Toon Link livery however carrying a tagline such as "Fast and Frequent links from Stanley and Consett to Newcastle City Centre" which would fill out on any Toon Link service when a route branded vehicle is unavailable. 

Castcading these Omnicitys to Stanley could also lease 4 OmniDekkas to a depot such as Chester Le Street, to cover up for their lost presidents and to replace another president or two.

Service 6 could be stopped to inter work with the X70/X71 at Newcastle by a timetable change.