incrediBILL - 6:50 pm on May 10, 2013 (gmt 0)
I don't think it's going to threaten their dominance but good curated content will always be sought after over random search results. I've always had places that I go where people with similar interests are posting information I find useful and refer to them over a search engine.
Don't forget Craigslist as there's lots of stuff you can find there that you cannot find in Google whatsoever which baffles me that many handymen, etc. have a website yet I have to go to Craigslist to find them because all Google offers up is Angieslist which won't let you see anything unless you register which isn't going to happen.