Is there absolutely no demand from South Shields or Sunderland for a bus to Metrocentre? Although the Metrocentre doesn't need any more buses, I do wonder if this would be an option particularly as I expect the BSIP could see the 27 withdrawn and buses integrated with the Metro.
The 20 could follow the 516 route to Marsden but then go right along Coast Road passing Whitburn to Sunderland if GNE wanted to run a bus around South Shields. Good to have a Shields to Sunderland bus service (this will likely be withdrawn when the Metro is extended to link Shields and Sunderland).
RE: Go North East: Service Suggestions v2