While I think that stadiums could be filled in Australia, I am not sure this will happen. August is winter in AU, and while neither Sydney, nor Melbourne are experiencing winters like the American NE, they can get cold, and singing two hours of rock music in cold air is not a good idea for any singer.
Sydney - avg low for August is 48F, record low is 36F, Melbourne is similar
Whole thing is even more of an issue, if you are talking NZ, Northern Island is more moderate, but southern Island it's really winter there. Auckland is on northern half though.
We shall see.
Stadiums? Based on what? They will almost certainly play in arenas/centres in Australia.
The last time (and I believe only time) Queen was in Australia, they played mid-sized venues and multiple dates.
Melbourne - Sports & Entertainments Centre attendance per concert 13,000, 3 concerts. [This is the attendance listed on Queen Concertpedia but I think it is overstated.]
Sydney - Entertainment Centre maximum attendance for concerts 13,000, 3 concerts. [Queen Concertpedia lists attendance at 15,500 this is not possible because it exceeds the legal limit.]
I do not believe Queen can fill stadiums in Australia except for a free concert. And this will be an expensive concert, not a free concert.
ETA -- here is a list of the largest Queen audiences. It predates QAL Kiev, so I added it.
Queen has had some big concerts but they are mostly one-off events, some free. They never did a stadium tour -- like One D, JT, Beyonce+Jay Z, etc. At their peak they were a top level arena act and that is what they are playing for this NA Tour. They have also play some big festivals.
Attendance:
Rio '85 (two nights) - 250,000 each (Rock in Rio) ** RiR claims it was 350,000 people each, most experts are skeptical.
London 9-18-76 - 150,000 (some reports claim 200,000)
São Paulo 3-20-81 - 131,000
Stevenage 8-9-86 - 120,000 (some reports claim 200,000)
São Paulo 3-21-81 - 120,000
Slane 7-5-86 - 95,000 (some reports claim 110,000)
Mannheim 6-21-86 - 85,000
Budapest 7-27-86 - 80,000
London '86 (two nights) - 72,000 each
Milton Keynes 6-5-82 - 65,000
(Honourable mention 1 - Live Aid '85, although it wasn't purely a 'Queen' concert)
(Honourable mention 2 - Kharkov '08, where Queen + Paul Rodgers played to about 350,000 people)
Q3 addition honorable mention #3 - QAL Kiev '12 Queen + Adam Lambert about 300,000 people
ETA #2: I am not minimizing the epicness of Queen in the 1980's....just for Rock in Rio they belong in the record books.
Both Queen RiR shows were filmed (on January 11 and January 18) and broadcast throughout Brazil by Globo. Each show was watched by nearly 200 million people in over 60 countries and in front of
350,000 people for each night setting a world record for the biggest paying audience ever at the time. It was later broadcast in the United States on MTV as "Queen: Live in Rio".
