Tyneside is pretty well served at the moment...
900,000 thousand people live in tyneside of which only 250,000 or so live in Newcastle upon Tyne.
Given that that area has one of the smallest car ownership levels, some of the poorest roads in England and is serious need of regeneration, I think I'd like to see some services looped via Sunderland, possibly via Middlesborough, another under-served area with a population of 450,000, and then onto Scotland. Both areas are crying out for a high-speed line.
Grand central will begin serving the area soon, so we'll see how it goes from there.