I should add that Sears had to stop providing mail-order houses - there was a peak and then a crash in about 1929ish (Great Depression time). Sears continued to exploit other retail endeavers, though, and remained a major player because of its pioneering attitude. And Ford did something far-seeing - as I heard it, he recognized nobody would drive cars - why would they, with no infrastructure in place? - unless he paid his employees enough money to buy the things. He also had a pioneering attitude.
Google will survive, but I do think that challenging its dominance is inevitable.