Hate to be all boring and serious, but I'm not convinced that Rio will be able to host the Olympics successfully. The logistical challenge is obviously immense.
Recently there was a UFC event scheduled to take place in Rio (insignifcant in size in comparison), and it had to be cancelled as it coincided with a UN conference and there weren't enough hotels to put people up.
I hope it's a success, this has been awesome and it'd be a shame for Rio to be a failure, but it is a worry.
There was also a UFC in Rio several moths ago and it brought traffic to a stand still.
Fingers crossed....