I presume this has been argued to death elsewhere by more knowledgeable people than me, but I can't see why it's a given that the SPL needs Rangers. Granted, Celtic will lose out, but then they have the near-certain championship to compensate. The closest potential challengers (eg. Hearts, Hibs, Aberdeen, Dundee Utd) will lose two big gates a season, but if they are competing for second place I could see them making that up over the rest of the home games. The others such as Motherwell*, Kilmarnock, St Johnstone, St Mirren might also benefit from bigger travelling supports from the first four named. Plus there would be 5 places up for grabs in the top six rather than 4.
As for TV money, overall cake smaller, but everyone gets a bigger slice no?
*very unfair on current placing I know!