Six tracks York Northallerton for HS2?

I don't think anyone doubts that if HS2 really serves the north east on existing tracks from York, that the Leamside will reopen. However perhaps what is bringing about Mr Mearns' MP angst is this? Reopen Leamside and try to run HS2 on existing tracks north of York. Is not York Northallerton effectively at capacity now anyway? Teesside traffic added at the latter.  So the bullet point: to run HS2 trains north of York and retain a good ECML service, another two tracks York Northallerton will be needed? Perhaps like Nightstar and regional Eurostar the promise to run the trains will be made and not delivered?