I honestly think the time will come very soon, when the Olympic Games will be awarded to whole countries (or very big regions) instead of citys and smaller regions (like the Rhein-Ruhr area). It would be a pity, that all those different athletes wouldn't be able to live in the same Olympic village anymore, but I don't see many other possibilities.
Only speaking about Germany, because I don't know the situation in other countries, but theoretically, we have almost every sporting venue here, just in very different places. Transportation costs wouldn't be too expensive either, if it is spreat over the whole country. And I don't think the costs for security measures will be much higher than for example during a Football Worldcup, which takes place in a whole country as well.