The issue with bidding is how many stadiums are there that can fit 60k+?
Wembley 90,000
Old Trafford 74,000 (new stadium will happen in the next decade at 100,000)
Tottenham 63,000
Anfield 61,000
Emirates 60,000 (exploring ideas to increase to 70,000-80,000)
Etihad 62,000 (works almost complete)
Birmingham 62,000 (could be completed within 5 years' time)
Newcastle redevelopment/new stadium 65,000-70,000)
West Ham 68,000
Chelsea (seeking to expand or rebuild to over 60,000)
There are seven stadiums that can accommodate 60,000+ now/next season, with there likely being 10 over the next decade. I'd also expect Villa and Leeds to seek to push capacity to that level in the future.
Warrington to Newcastle, UK is like 4 hours one way
The only real possibilities for the Super League grand final are Old Trafford, Etihad, a redeveloped Elland Road or one maybe Anfield or Everton
The historical factor for the Challenge cup and Wembley is the "national stadium"
Most European nations have this concept, Australia not quite. It'd seem strange to us
Most European nations have a primate city that dominates all aspects of life, so of course they're going to have national stadiums. They are no different to Australian states in that sense.
The big nations that are like Australia have differing approaches. France and England do have national stadiums, whereas Germany, Italy, Spain, Turkey, Poland, Netherlands, Russia, Ukraine etc don't. England wouldn't have one either if the FA didn't own Wembley.