As all the space geeks know, the ISS is planned to operational to 2016, only six years after construction is completed. Afterwards, it will either sit in space until it falls to Earth, or more likely, there will be a deorbit plan to have it burn up "safely" over an ocean.
Everyone following it knows the ISS was pretty much a "white elephant" space project. There will be no future shuttles servicing it (after 2010), and its unlikely the Russians will keep servicing it, out of its own wallet. But with the rise of space programs outside of the big 2, could it not be possible to keep the ISS going beyond 2016?
After all, space station Mir functioned years beyond its original closing date. You have the Japanese, the Indians, and the Chinese all looking to make a mark in space. Perhaps the ISS could be the future launching point of space tourism. Talk about the most exclusive dining experience. What would need to be accounted for to allow this possibility to come about?