The real hit to the economy isn't going to be the housing slowdown per se, but rather the lack of all that refi and home equity loan money sloshing through the economy. Homeowners got used to the idea of their homes being a magic cash machine spitting out a good $10-30K of home equity loan money every year. Anecdotal evidence suggests many of these homeowners are now turning to credit cards to substitute as a source of "extra income." Of course, that's only going to last so long.
Of course, this all goes back to the fact that America's standard of living peaked in the 1970s, and the real income for the working class has been declining for some time now. This accounts for all the deficit spending and asset bubbles built with the tacit consent of the Fed as increasing amounts of pixellated cash are shoveled into the growing income gap. This only works for so long...and sooner rather than later the music is going to stop.