The amount of investment in new buses is likely to be minimal in the next few years I reckon, maybe some cascades from London will be possible.
At least some of the Arriva fleet heading in/out of Newcastle have already had mods to Euro 6 such as Jesmond's StreetLite's and the X12 Pulsar's.
We now have another year to worry about CAZ in Newcastle and how that affects things which will obviously be sorted somehow, someway.
Also as ever with these suggestions, Arriva North East exist South of Newcastle and not just the X12! The next buses for the chopping block are likely to be the 05 plate OmniCity's and probs B7's as well.
Arriva NE order suggestions