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In the past 8 years (2010-2017) Melbourne has hosted 6 Wallabies Test matches, including one Bledisloe Test and one Lions Test. In the prior 8 year period (2002-2009) Melbourne hosted 8 Wallabies Test matches, including one Bledisloe Test - there was no Lions tour of Australia in the period 2002-2009.
So it is simply business as usual for International Rugby in Melbourne for the next 8 years.
The main difference in the next 8 year period (2018-2025) is that as a result of the now poisonous relationship between the ARU and the WA Government, the WA Government will probably not fund any Wallabies Test matches in Perth after the Bledisloe Test in Perth in 2019. That leaves the ARU with the problem of having to find a State or Territory Government who is willing to fund domestic Wallabies Tests to the same level that the WA Government has been doing for the past 20 years.