That's a great example to contrast with the S&C (which obviously remains open and only sees a Sprinter every couple of hours, rather than the amazing Thames Clyde Expresses and Nottingham - Dumfries services and half hourly freight and regular steam specials and HSTs from Leeds to Glasgow and all the other wonderful things that would surely be promised if BR/Portillo had closed it down in the 1980s)
If Skipton - Colne had remained open then my guess is that today's service would have just been at lest an extension of the hourly stopping DMU that served Colne (i.e. a single 142 for decades, recently replaced by a single 150) - low speed single track with a loop at Colne - I can't see it having been electrified when BR were doing the Leeds - Skipton line (let's face it, BR had a lot of other priorities that didn't get wired at the time) - the DMUs would trundle up and down with a couple of dozen passengers at best...
...but it was closed, which allows the daydreamers to envisage scenarios where it's a double track electrified line taking Hull - Liverpool expresses, removing lots of freight from the Diggle line, finally giving East Lancashire a direct link to the prosperity of Leeds (if you ignore the long established hourly service via Hebden Bridge!) - the SELRAP website (
https://www.selrap.org.uk/Project.html) even talks about "the possibility of a direct link to Manchester airport from points from Shipley to Skipton" (because of course the Castlefield corridor needs new services!) and it'll "massively drive economic growth, open up new job opportunities, encourage business growth and stimulate new development throughout East Lancashire" ..."new jobs, businesses, economic growth and greater prosperity" (two hundred and fifty thousand people are quoted as the population of East Lancashire, which suggests that they are hoping nobody notices that a large number of those people already have an hourly service via Hebden Bridge!)
It's a lot easier to grieve for closed lines and imagine just how amazing they could have been today if only we had hundreds of millions of pounds to re-open them - much more exciting than dealing with the reality of several lines where the hourly Sprinter rarely has passenger numbers that would trouble a minibus