Very thoughtful, informative answer. I think many people with similar experiences fail to distinguish between those who are terminally ill and those whose lives are merely inconvenient for others.
Interesting story in the St. Pete Times about a similar situation to Terri's. In this case, the husband let the parents care for the daughter, he divorced her and moved on with his life. Too bad Michael Schiavo didn't do the same thing.
http://www.sptimes.com/2005/03/26/Tampabay/Parents_endure__cling.shtml