It would just take at astronomical amount of capital to challenge Google at generic Internet search, and the few organizations with that capital are pretty clear they don't think it's a good bet. For example, Amazon is quite content just being the place you want to go to first for the things you want to buy, as that is obviously the most lucrative area.
Even in niche areas, I think it's still an enormous task to challenge Google. Despite the fact that 90% of my searches for "WTF does this stacktrace mean?" end up on StackOverflow, I invariably start my search on Google because every now and then it gives me useful non-StackOverflow tidbits, and I know I can always drill in more with specific tags on StackOverflow later.