Since it's unlikely to get 45% of all internet subscribers, consider a reasonable subset of them such as just America/Europe subscribers. However, if it were $50 and I had access to every movie/TV show ever made, I'd pay that every month, and they would probably only need the America/Europe market. Maybe an extra $20/mo for access to 'new releases' provided they were available on the standard plan after maybe 60 (90?) days. They could even do an extra 'HD' surcharge of $20-$30/mo I used to pay more than that for cable and only got access to whatever the channels were running at that time (maybe time-shifted with a DVR, but still required them to run it at some point while my DVR was recording and still had to deal with commercials). I would definitely pay that for access to everything that I could easily search and select from a list and instantly start watching something.
Netflix Instant is nice and all, but it doesn't have the best selection. I've found most of the streaming sites (Netflix Instant, Hulu Plus, and Amazon Prime), all have about the same stuff. I stream a lot from home, but we always run the risk that the streaming provider could drop a show I like at any point. I think paying a premium to ensure it's always available and that everything ever made is available, is worth it.
Obviously, this is an amazing idea that would revolutionize media content for this new internet age, which means it will never happen.