I'd say you or I might not make it an entire week in the wild, but Fossett might, if he was carrying at least some water or located a nearby clean water source. But I still think he died of injuries sustained in the crash.
As for McPherson, similar but different, you know how many people who died in WTC 9/11 or Katrina who are living somewhere in the world under an assumed name? At least a few. Every large multi-fatality, missing-body disaster at least couple people use it as an opportunity to drop out, run away and start over.
I know Fossett has a reputation for being an unusually resourceful person, but there was no reason for him to carry water or food for a local flight, and if he'd walked out to any visible location he'd have made an effort to be found. Still the idea of him being killed in such a routine local flight is mind-boggling to me. If that turns out to be the result, it will go down in history as one of the great ironic deaths, like Gen. George Patton being killed in a traffic accident.
If he's not found soon, dead or alive, I'm going to continue to wonder if he pulled a Sister Aimee.