Unless something changes, New Zealand and Australia will be become fringe economies in the International Rugby sphere by the end of the decade. Europe, Japan and even the US will continue to make it increasingly difficult to maintain a competitive domestic game featuring the best players.
RWC, Lions Tour Olympics might help Rugby Australia tread water over the next 6-8 years, but these are one-off events . Likewise New Zealand might be able to hang on longer then Australia through better pathways and a PE injection through selling off part* of the ABs, but that only goes so far. Without a competitive club competition, and a 'Rugby Championship' product that domestic & international broadcasters are willing to pay top dollar for, Australia and New Zealand are going to struggle to compete going forward.
2 things need to change IMO:
1) Rugby Championship as a product needs to be reviewed, South Africa need to commit or get out. Japan and Fiji as candidates to join needs to be considered. A Womens Rugby Championship has to be established.
2) Super Rugby needs to incorporate a 'Champions League' featuring Japanese clubs, there's no two ways about it. Australia and New Zealand cant compete with the wages on offer in Japan, but a Champions League at least allows them to tap into the broadcast market on offer.