Here is a must read comment by "dougr" on TOD.
He says the well bore structure is compromised "Down hole". That was the reason Top Kill failed. That also means BOP is in danger of falling over. If the well becomes completely compromised, even the bottom kill using releif wells becomes difficult.
All of these things lead to only one place, a fully wide open well bore directly to the oil deposit...after that, it goes into the realm of "the worst things you can think of" The well may come completely apart as the inner liners fail. There is still a very long drill string in the well, that could literally come flying out...as I said...all the worst things you can think of are a possibility, but the very least damaging outcome as bad as it is, is that we are stuck with a wide open gusher blowing out 150,000 barrels a day of raw oil or more. There isn't any "cap dome" or any other suck fixer device on earth that exists or could be built that will stop it from gushing out and doing more and more damage to the gulf. While at the same time also doing more damage to the well, making the chance of halting it with a kill from the bottom up less and less likely to work, which as it stands now?....is the only real chance we have left to stop it all.