Notre Dame's addition would add exactly 0 states to the Big Ten footprint....you think Delany is turning them down?
It isn't only about TV subscriptions, advertising revenue is projected to eventually make the network more money than subscriptions do....and in that event, Duke/UNC are VERY valuable. Duke/UNC are two of only four basketball programs in the country that can draw football type numbers on a consistent basis during basketball season. If the Big 10 is looking to drive up advertising revenue, adding Duke/UNC games to the BTN would be a very good move. You know that TV sets in Minneapolis, Chicago, Columbus, etc. are going to be tuning in when their respective schools play Duke/UNC in basketball.
In terms of subscriptions, adding Duke/UNC/UVA would be about ideal. Delaney has acknowledged that the Big Ten's decreasing population is "problematic". Adding Virginia/North Carolina to the footprint would be a very savy move to help the conference population trends balance out a bit. NC currently has a population of 9M, but at its current rate of growth, it will reach 12M by 2030. VA is currently sitting right around 8M, but by 2030 it is projected to be around 10M. Also, adding those three makes a four divisional format work out well.....you can let PSU lord over the "Colonial Division" of the Big Ten - PSU, UNC, UVA, Duke. I've always preferred that system because it would allow Iowa to be in a "Great Plains" Division with UNL, Minny, & UW - preserving our traditional rivalries.
Your former point about removing Duke/UNC from NCSU is noted. I think that is why I'd push UVA really hard though - Duke/UNC/UVA are nearly as close of rivals as Duke/UNC/NCSU. Further, current Big Ten teams bring home nearly $10M more per year than each team in the ACC - it would be tough for an athletic department to outright turn down a $100M dollar offer given the costs of participating in FBS football today.