Experts agree BP oil well casing has failed: Relief wells ma... - Care2 News Network
This is the article that states how the well casing has already failed. For a nightmare scenario, read the comment below the article that states what will happen if the well were to collapse due to the blowout.
What may happen is the two relief wells may also blow from the tremendous pressure and we will end up with three times the oil flowing into the Gulf than what is currently killing the ecosystem and this may be the BEST case scenario. The worst case could be a complete collapse of the sea floor above the oil field causing an explosion comparable to Mount St. Helen's eruption only 50 miles offshore. The resulting tsunami would completely destroy the entire state of Florida because it is barely above sea level. The death toll could easily be in the 10's of millions as, as much as a mile or more of coastal shoreline around the entire Gulf of Mexico would be swamped by the tsunami.
So there you go. The worst has not even happened yet. A worst case scenario would leave 10's of millions dead, the entire gulf wiped out, and the state of florida crumbled into the sea floor.
I think this is almost apocalyptic, but the science behind the article says that it all could theoretically happen. I don't think it will be this bad, but we probably really truly haven't seen the worst yet.