You are right to point to Roubini's latest piece. But your title is absurdly irresponsible and misleading. Roubini said only that there is a rising risk of an L-shaped depression:

At this point the recession train has left the station; the financial and banking crisis train has left the station. The delusion that the U.S. and advanced economies contraction would be short and shallow – a V-shaped six month recession – has been replaced by the certainty that this will be a long and protracted U-shaped recession that may last at least two years in the U.S. and close to two years in most of the rest of the world. And given the rising risk of a global systemic financial meltdown, the probability that the outcome could become a decade long L-shaped recession – like the one experienced by Japan after the bursting of its real estate and equity bubble – cannot be ruled out.