Hmmm. I don't know. I think Locke is dead. Locke laying in that coffin takes place what, some three years after the Oceanic 6 come home right? My theory is that Locke eventually had to move the island himself in order to protect it. By doing this he was no longer able to return to the island and of course when off the island, Locke is once again paralyzed.
This would be quite a hard situation for Locke to deal with. I could see him committing suicide over it.
__________________
|