Hi Tim. Yes, an opportunity lost, for sure. Ravenscar Tunnel, if opened out into a cutting (as, of course, is was intended to be...) would have taken away a big operating problem. OK, you'd still have reversals at both ends, but with DMU stock that's not a major issue.
I'm not sure that the Whitby-Boulby section, including that bridge at Staithes, could have a business case though. Too many problems with coastal erosion & infrastructure. You've still got the Esk Valley, of course, and route duplication undermines the case for that section further.
Mark