http://www.dailytech.com/NASA+Plans+to+DeOrbit+100B+ISS+in+2016/article15680.htmMichael T. Suffredini, the NASAspace station program manager, has announced that despite the fact that the ISS is only now nearing completion, there are already plans to de-orbit the station. The last of the components for the ISS are set to be in place next year and according to Suffredini, the station is currently planned to crash back to Earth in 2016.
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Possibly with some lobbying in the next 5 years they will get funding to not go forward with this current plan.