Why not simply shift them into continents rather than host countries. You can potentially exclude Australasia for being too small... but North America, South America, Europe, Asia and Africa could all host an Olympic games on a rotating basis every twenty years. The games themselves would then be split between countries and available cities. Disruption would be lower in each city and the competitive element from each country/city would all try and outdo each other on their individual events and hosting prowess. If it came to Europe it'd be great to see London, Berlin, Paris, Dublin, Madrid, Riga, Budapest, Rome, Vienna, Lisbon and all the others hosting their own events.

You'd make money in tourist travel between cities if they wanted to do multiple events, no individual city or country would be overburdened with hosting a billion athletes and there'd be more jobs available in each place for the local population. Also, if smaller cities were given the chance to host one or two events they'd probably get themselves a whole bunch of returning tourists. Most people who comes to the UK don't really venture out of London very much. Smaller niche events could go to smaller niche cities - here in the UK we have smaller cities like Glasgow, Manchester and Cardiff which have good facilities but aren't big enough to host a huge amount of stuff. We could probably whack the synchronised swimming out in Bath if we wanted to give it a Roman feel.

If this happens, I want to be on the Olympic committee as a well-paid consultant.