A forest grows for hundreds of years. Many trees are large and mature. There is much life in the forest, both flora and fauna. Some trees die and their dead wood litters the floor. One dry day, it is inevitable that a fire will burn the wood. Whether it is done by human hands, or by lightning doesn't matter for the purposes of this story.
The fire sweeps through the forest causing death and destruction. When the fire burns out the once emerald green forest, full of life is now a charred, dead, alien world. It is a very sad place. The animals that survive miss the beautiful abundance of their home, and mope around depressed, scraping for any bit of food they can find.
Many animals leave to find food in another forests. Other animals stay and tough it out. Rains come and wash the charred remains of the burnt forest into the soil providing nutrients for the soil to grow new life. Trees and plants slowly begin to return. The forest is springing new life from the ashes of the old trees.
Hopefully you see the analogy with the housing market. The fire is still burning in the form of foreclosures, although we may be closer to the end of the fire than the beginning. But those foreclosures will clean out the dead wood and provide nutrients (affordable housing) for our housing markets to once again grow.