Exactly - none.
I am talking about commuting from Whitby. That would involve transversing that which is now the NYMR. This has always been a very low speed stretch of railway, and there is not an awful lot that could be done about that. Road id a far more practical alternative. Tourist traffic is the same. The NYMR only gets involved, as the journey offers a pleasant addition to a day out in Whitby. A 158 doesn't quite match this.
Lets be totally honest. There is no substance to the suggested scheme. It gets suggested a couple of times a year, and has been regularly for the 20+ years that I have been volunteering at the NYMR. What you might see are some capacity improvements between Grosmont & Whitby, and if the political will is there, maybe a Swanage style Park & Ride Scheme at Pickering.
As for the rest - I just don't see that there would be a market. It went out with the Victorians.