Because the remainder of the US' involvement in the ISS program is being
refocused on countermeasures for astronaut health on long-duration
missions
to the moon and/or Mars. This work is supposed to be complete by 2016.
This
allows the money otherwise spent on ISS to be redirected to the moon/Mars
program after that date. Building a replacement station would defeat the
purpose.


How long is ISS supposed to last?

Doc

--
And if you wish to avoid crushing social embarrassment, it's red wine
with dwarf, white with fetus.

Semolina Pilchard