Its pretty hard to say. Super Rugby’s success drained interest from NPC, but as noted below Super Rugby just doesn’t spread itself around New Zealand much anymore and there are large population bases that don’t get many games nearby. One NZs largest population centres in Bay of Plenty has a 3 hour round trip to get to a Super Rugby match, and there just aren’t that many folks who will do that for a 7pm kick off.
Palmerston North - Wellington is a 3hr30m round trip, Whangarei to Auckland is 4 hours, Napier to Wellington is 8 hours, Nelson to Christchurch is 10 hours. You might do those trips for an All Blacks test match, but you’d have to be fairly die hard to do it for what is in effect just a quite high level club footie game.
So my thinking with that fantasy franchise setup is to get back to 12 teams in Super Rugby, make the Australian clubs more competitive and then in order to balance downgrading the NPC move Super to a double round-robin (same as the NRL is). That’s 22 regular season games which is a lot more than now which helps the franchises make more money (because the live attendance is much more important for them) and more matches gives them the flexibility to spread them around a lot more.
The NPC would have to make way to give this competition room - potentially splitting into a smaller, more development focused regional series and proud provinces like Hawkes Bay would have to accept the trade of Super Rugby games instead of NPC filling McLean Park. But getting 4-5 guaranteed Super Rugby games a year with a new Eastern franchise splitting the remaining 6-7 with Rotorua & Mt Maunganui is a hell of a lot better than 1 every other year.
Cost cap… there’s a lot of merit to spreading the talent around but i’d have to think about how it could work in the NZ context.
How spread out is the rugby fandom beyond the higher population areas in the south - Perth/Dundee west to Irvine/Ayr etc? Because if 90% of the fans are in that area then it does make a lot of sense to play so much in Murrayfield - especially if the tickets are selling. Its just so much closer than most rugby fans in NZ.
But I agree with you, its hard to get your local people interested in the game if you don’t bring the game to them!