It may well be possible. If so, I think it will be well into the future. Right now, for the ability to host such an event, you're talking about the largest multi-sport games and the second largest multi-sport games in the world. By putting those two events together, and with the magnitude of the logistics and the timelines, it would really have to be cut back. Both games would have to be significantly cut back in the number of athletes and the number of events that occur to be able to do that in one city.
It is certainly debated in all circles and it's something that keeps coming up all the time, so at some point that may occur.