The probability of such a global failure occurring within the next 100 years strikes me as near 1.0, and thus possibly more pressing than any of the events listed above.
http://www.nickbostrom.com/existential/risks.html
In these terms this could be a 'crunch'.
So suppose we are worried that a die-off in industrial nations will actually make it impossible. Isn't this risk (that there is a major catastrophic disaster for industrialized nations and this disaster prevents a singularity from ever taking place) much smaller than the risk that the singularity goes badly when it happens? If so, then this supports the spirit of my original comment: worrying about the singularity going well is more pressing than worrying about major shocks to civilization which do not completely wipe out humanity.
Isn't the risk that a large industrial collapse happens and it prevents a singularity from ever taking place much smaller than the risk that the singularity goes badly? If so, then this agrees with the spirit of my comment: worrying about the singularity going well is much more pressing than worrying about catastrophes that do not immediately wipe out humanity.