Apologies if this seems hopelessly naive, but has anyone posed the question to Sky - "Okay, it looks like we may have a wee problem here in providing you with 4 Old Firm clashes for the next few seasons, so what's the script on the TV contract if we can't deliver?"
Surely it is possible to get a ball park figure (or no figure, in the very worst case scenario) that would allow some sensible analysis of whether or not there really is a bogeyman out there.
Reminds me a bit of the Gruffalo story!