I think you will find the Gold Coast will be in 2007,announced next year,and then once the new Tv contracts are into place possibly the following scenario Rabbitohs to Central Coast(if they cant get a new redfern oval up and running),then either a relocated Sydney team to Perth in 2008 or a brand new team,and if the latter then Wellington NZ will be added to make 18 teams.
Unfortunately the Sydney clubs have become too dependent on pokie machine money,which will dry up somewhat next year,and this means a couple of clubs will be left with no alternative but to relocate or die-I hope not.
As far as support base in Perth goes previous NRL matches have drawn large crowds,the Reds initially but it dropped off when they lost their impetus,there are still many east Coast aussies ,Kiwis and Nth Englanders who have migrated to that state,and who have supported league in the past.It would be a matter of organising games at different days or weekends to the union. Like any sport if the team is successful,you get huge numbers of bandwaggon jumpers,as happened with the Storm in 1999.