I have thoughts. But if we go further on this the mods will probably need to pop this thread into the speculative discussion area.
Looking at the ORR figures and taking all journeys between the local authority areas rather than individual stations, we have:
67,000 journeys between West Yorkshire and Edinburgh
37,000 between West Yorkshire and Glasgow
For comparison, Birmingham and Nottingham are both in the 90-100k bracket. These are shorter journeys with hourly direct services.
Other largeish destinations with no direct service to WY and about the same journey time as Glasgow (Oxford, Reading, Cardiff) are below 10,000.
This suggests there is actually a reasonable level of demand for WY-Glasgow.
If the railway wanted to test the appetite for this, the lowest effort option would be to 'borrow' three hybrid trains and run 3-4 services each way per day with minimal stops on the S&C then fast via Beattock. You might be able to get Leeds-Glasgow down to 3h40 (it's currently 4h13 with 18 stops between Leeds and Carlisle and an 18 minute change there).