We've already discussed at length that it would make the most sense to limit the Olympics to a handful of host cities and just rotate it among them. Stick to the ones that are large enough and with available infrastructure to limit the cost of building for them, and prevent the decay of later disuse. Los Angeles, for example, could immediately host a summer games without incurring much if any cost of building. A handful of other cities meet those criteria.
Previously the graft and corruption of the IOC prevented this-- they received a lot of money and perks from competing cities-- and so it was in their best interest to insist upon competition and constantly spread it around. But now they're having trouble finding cities to bid at all, and that particular gravy train is coming to an end.
I'm certain the IOC will find new ways to slime its way into some unearned cash, but if it means we can end this constant cycle of spend/build/decay then it's a net positive.