What Google has actually done is create a powerful infrastructure. The shape of that infrastructure influences everything that goes online. And it influences the allocation of mental resources of everyone who interacts with the online world. But there isn't much to the real human world that isn't shaped by the mental activity of the people in it!
That's a lot of power to put in the hands of a company that now seems interested, mostly, in identifying core mass-market services it can use to maximise its return on investment. Now in the short run, that may mostly be a problem for all of us. To the extent that we become worried about this phenomenon, we may go out and find back-up services or other alternatives. This will be less convenient and more costly, in terms of time and money, but those sufficiently foresighted might feel it's a better option than opening up gmail one day to read that the email service, and the 10-year's worth of communication it holds, will soon be gone.
But in the long run that's a problem for Google. Because we tend not to entrust this sort of critical public infrastructure to the private sector. Network externalities are all fine and good to ignore so long as they mainly apply to the sharing of news and pics from a weekend trip with college friends. Once they concern large swathes of economic output and the cognitive activity of millions of people, it is difficult to keep the government out. Maybe that deterrent will be sufficient to keep Google providing its most heavily used products. But maybe not.
