I think the rotation idea is the best. Every ticket to a Superbowl sells and people will pay any price to go. The cities and teams can plan well in advance to prepare for the event. A team with a Superbowl 10-15 years down the road can use this as leverage for freshening up the stadium or getting a new one. As said before, they play in bad weather during the season. Only domed stadiums in the north to host because of weather doesn't matter since the stadiums can deal with their own snow problems. I remember a few years back the Giants had a huge storm before a playoff game and brought hundreds of people in and paid them $10 hr to clear the seats and walkways. The game went on. With a packed house.
These were Giant's fans. I believe this also happened in Green Bay, Philadelphia and a few other playoff city teams as well.
New Tork, Baltimore, Washington, Chicago, all have tourism on a regular basis throughout the year. So if the Super Bowl were to be held, these cities are prepared. There are other cities like Cleveland, KC, Green Bay, where tourism is limited. So if 80,000 people, not including media show up, even with 2 years notice, they would be prepared.
Don't misunderstand. I would love to see the game played in Denver, KC, or Foxboro. I just don't see it happening.