The US government has estimated the overall loss projection for the housing majors Freddie Mac and Fannie Mae to hit over 300 billion US dollars by the end of next year, in a worst case scenario. That would indeed depend on the housing sector remaining weak and also on the assumption that the unemployment levels would only move down slowly.
If the globe gets into one more recession or if there is some sort of shakeout in the US finances, which can be triggered by China or by Japan, then the loss for these housing majors might shoot up further which has not been factored in.