If Arriva won the contract, is there any reason why these services could not remain operating out of Faverdale? While franchising as done elsewhere seems to come with services packaged with depot premises, it doesn't have to be like that.
Arriva X1 and X22 are a similar situation of "County Durham services" being done from a depot outside NECA (though a smaller proportion of Stockton depot's work.)
The boundary of NECA with Tees Valley is the main one with these issues, although 685 is also an example. I suspect it could operate out of a depot at Hexham under franchising.