There's a lot of paranoid people. The AFL and NRL don't have to close down for the 8 weeks, they just have to vacate 12 or so stadiums. Other than the benefit to the economy this will also mean upgraded stadiums. For instance Suncorp might go to 60000 and ANZ to 90000, these stadiums and others probably won't be upgraded unless the WC comes here, possibly a whole new stadium in Western Sydney. Governments are notoriously frugal with stadiums and loathed to upgrade them, this WC will means upgrades we'd almost never get. The NRL should be using this to make sure it gets the best deal, ie its stadiums upgraded and not the AFL's. There will presumably be compensation.
In the 8 weeks the WC is up they could take 4 weeks off when its on and tour Europe or simply have a rest. Or they can play through and use smaller venues, country venues and NZ venues. In the 4 weeks leading up while the big stadiums are closed why not play in places that never get NRL games. For example play the Cowboys in Cairns, Broncos in Ballymore or Toowoomba or Rockhampton etc. Play games in Wagga Wagga etc. Host a whole round in NZ etc. Its the end of the world only if you can't think outside the box.
Put it this way FIFA will pay to upgrade our stadiums and pay us to take games to the bush and expansion areas like NZ, all for an at worst 4 week lay off in the competition.
There's no need to copy the insular attitude of Victoria and cry when a new sport comes to town.
