But who is going to use a Metro connection out of Sunderland and a bus connection out of Durham when both would be slower than their respective city centre stations once the time for the connecting journey is added in?
Your making the assumption that that Passengers who use Darlington,Durham and Sunderland are not travelling to other places once they get off the train. How many passengers get off at Durham, jump on the park & ride Bus to pick-up their car for onward travel? or have someone pick them up from the Station?
The Same with Sunderland, How many will get off a train at Sunderland and then get on board a Metro train to there final destination?
Darlington is the same. With the latest timetable change, if your travelling from Thornaby-Saltburn to anywhere South, NRE suggests changing at York not Darlington!!!
When I travel, I have to check Trains from Thornaby, Eaglescliffe or Darlington all three give different "Total" journey times (from Home),and prices also vary significantly. It can be quicker and cheaper to travel by car to Darlington than get on at Thornaby.
And why would anyone want to use that when all trains but one stop at Darlington and most at Durham? Leamside/Stillington would have a very slow exit from Newcastle and severe restrictions at Pelaw, Victoria Bridge and Stockton. It's possible as a freight bypass and perhaps a local passenger service to regenerate communities along the route, but no way will it ever be faster than the ECML.
Of course it will never be faster than the ECML, I never said it would. But it would give you scope to maybe send an odd KGX-NCL stopper via this route or the odd TPE (NCL-Liverpool) which would free up capacity on ECML for KGX to EDB services