My understanding is that the ISS is supposed to be some sort of research platform. Moreover, it was purported to be some sort of nexus for launching to the Moon, which was supposed to be the intent since 1969 as being the springboard to Mars.
Never happen; we'll never get to Mars (ever). With the way the energy crises is unfolding, and the way the world's econcomy is decaying: there's not enough money in the world (in real terms) to get to Mars. And if the bird flu strikes, or China invades Taiwan simultaneously while N. Korea invades the South: FORGET IT we're not going to Mars.
Not that we need to go to Mars either, unless there are commercially viable and exploitable reasons to do so (autobots can do whatever research is necessary).
It's plausible that we may go to the asteroids for mining operations (for raw materials to build stuff in orbit so as to eliminate the energy budget of launching finished materials into orbit). Or we may go to Saturn ostensibly to nudge large chuncks of ice into Earth orbit for use as fuel.
However, I'm extremely pessimistic that will happen in our, our grand-children's (or even their grand-children's lives).
This is what the German scientiest in the early space program pushed for. They reasoned that we could land and recover robots on the moon far quicker, easier and cheaper then a man.
It was the Kennedy-Johnson administrations that insisted we had to put men on the moon, so now our space craft had to support life as well. Size and environmental support became an issue.
Then our astronauts rebelled at being "spam in a can" and insisted on having some flight controls and this increased the demands on the program.
The Germans were also opposed to the whole shuttle concept but by then the lines had been drawn and they were being eased out of the program for the most part.