It seems to me that there is still a TON of archviz being done these days. But the economic situation is definitely putting "the squeeze" on smaller 3D shops -especially those that are doing primarily residential (even large-scale housing development) projects.
Smaller shops may not have the capitol to weather this downturn -and will be forced to close or to become purchased by larger operations.
Larger archviz studios (and larger 3D shops in general) will probably come out of this downturn looking pretty good.
My advice is to look for work with these larger company's.
There are many shops (even large studios) who are on hiring "freezes" but are still taking on jobs they can't turn around in time. This means there are opportunities for freelancers with the right connections.