It wouldn't. They only way a mid season fixture is going to remain strong and gain support is to have the best England has to offer playing against each other for a national jersey. That means Yorks V Lancs, the overseas players coming to this country will be getting weaker and older as the years go by with tightening of quota ruling. Who cares about the minorities of Londoners and who ever else might have a sprinking of cultural influence on the sport. Yorks V Lancs is where it's at(Don't rule out a Cumbrian side but ATM players from that area must choose Yorks or Lancs). Who the hell is going to support and play for a combined Celtic Nations team, who the hell is going to support a Exiles team and who the hell is going to support a Wests Vs Easts team? I wouldn't I'm not an Eastsman or whatever you want to call it, I'm a Yorkshire man and I would support Yorkshire, and I imagine that fellow Yorkies and Lancs would get behind their county if we give it chance to build it's profile.
Make the most of the support in the heartlands and really ramp the hype up. Clubs must also buy into it, and if they really have the future of this game in England in their hearts then they would, IMHO.
We need to make this game meaningful for fans and players.