Just racking my brains and thought (for what they are worth), to outline my thoughts on some of the changes in Sunderland.

I will suggest alternatives in the route suggestions thread.

We have all been told, that the 35 in its current guise, is profitable.
Despite it having issues with reliability and the Houghton - Rainton Bridge - Houghton section often carrying nowt but fresh air out of the peaks.
It seems strange, to risk this profitability, gambling it in areas (in North Sunderland and the 71 route), which often struggle to justify smaller vehicles (assuming the Mercs stay on the 35) and are left at the whim of more frequent services.
I assume, they are hoping the newer vehicles, will stimulate growth in those areas.

The 20 struggles to keep time as it is.
Without getting into the debate about reliability again, vehicles have been seen broken down and one was off the road for a significant period of time.
To extend it to Shields, whilst possibly increasing the profitability of the route, can only lead to issues with its reliability - unless, a spare vehicle or two is left at say Park Lane.
Reliability and the location of stands for competing services in Park Lane and Shields, may lead to passengers choosing the competing service.

The X36 is being reduced in frequency on the Newcastle stretch - it hasn't taken off as anticipated.
Maybe it needs marketing as a through service?