Would an Olympics in 1956 butterfly away the demise of Juan Peron?
Depending on the success of these Olympics, the IOC may shy away from returning to the Southern Hemisphere so soon. It took 44 years between the Melbourne and Sydney Olympics after all.
Perhaps something like this could transpire:
1956 - Buenos Aires, Argentina
1960 - Rome, Italy
1964 - Tokyo, Japan
1968 - Mexico City, Mexico
1976 - Montreal, Canada
1980 - Moscow, USSR
1984 - Los Angeles, USA
1988 - Sydney, Australia
1992 - Barcelona, Spain
1996 - Athens, Greece
2000 - Beijing, China
2004 - Paris, France
2008 - Seoul, South Korea
2012 - Chicago, USA