I think the ISS should be boosted to a high orbit that will not decay for, say, 20 years (not sure how high that would be). It can still be accessed by the CEV. Spare parts can be delivered by unmanned rocket. The ISS could still be manned: suppose we needed assembly of a large spacecraft for a manned Mars mission, entailing alot of time for on-orbit assembly, maybe many months. Astronauts would then have the choice to stay aboard either the ISS or the CEV for the duration of the assembly operations, and have the use of the ISS robotic manipulator for man-handling multi-tonne pieces of equipment. Even though it could not deliver the large pieces of equipment the CEV could definitely be used for crew-changeout and re-supply at that higher altitude. The ISS isn't junk. I see potentials.

The problem with the shuttle is that it has failed a fundamental overstress test, AND the cause potentially affects all the shuttles. This is viewed therefore as a potential "common cause reliability failure". Design revisions could prevent the problem, but it appears that the proposed revisions, regardless of how reliable they may be themselves, do not address the cause. They rather attempt to increase availability by reducing repair time of the machinery currently in use. In engineering this is not really the desired solution, and is only used when the design is set in stone, the equipment already built and in use, and it simply isn't possible to redesign it without shutting down the space program and taking the vehicles out of service. I mean seriously, there are 3 shuttles! These are big ships! And there are alot of missions to complete!

Put simply, fixing the root cause might justify retirement of the shuttle and development of a totally different spacecraft that completely eliminates the problem. But we already know that -- correct?