It showed that the cognitive areas of the brain were considerably less damaged than the areas responsible for interfacing with the outside world. Since there was apparent motor function, it would probably have been possible (were it not for Michael's prohibitions) to teach Terri to communicate (whether via blinks or some other method); then SHE could have been asked if she wanted to keep being fed.
The localized brain damage observed in the autopsy is interesting for another reason: it suggests very strongly that Terri's heart stopped because she suffered brain damage, rather than vice versa. The only thing I can think of that would have caused such a thing, outside of physical disruption (e.g. a sleeper hold) would have been a blood clot. While I am all too aware that blood clots can be fatal (late wife), it would seem rather strange that a healthy woman would have such a blood clot sufficient to cause cardiac arrest, but then have the blood clot disappear without a trace and never have any other serious blood clots for many more years.
Terri Schiavo suffered severe, irreversible brain damage that left that organ discolored and scarred, shriveled to half its normal size, and damaged in nearly all its regions, including the one responsible for vision, according to an autopsy report.