I don't see why the Four Nations needs to go at all though, it's typical RL that we're finally starting to get somewhere in terms of a regular and logical international schedule and then they want to start messing with things. I'm all for doing more to get other nations involved, for example both Scotland and France should have been invited to make a 5 Nations in 2016 while everyone else is playing World Cup qualifiers, but there's no need to make wholesale changes to the format. If the Aussies don't want to play then who cares, they aren't that important, invite Samoa or someone instead.
And bending over backwards to accommodate 'tours' is f**king stupid, nobody would think that they were a good idea if it wasn't something that was done in the past, in a now bygone and irrelevant era. There is literally no logical argument for their existence other than 'it's traditional' and who cares about tradition, tradition has got us nowhere for the last 100 years.