What happens during wartime when civil liberties are curtailed? I suspect each company will have to follow their law of the land which might involve regrettable use of data. In other words I dont have a lot of trouble believing that the Googles and the Facebooks of the world will be good stewards of data in normal circumstances (Its in their self interest after all).
The other issue worth thinking about is that we are in the midst of the golden age of building networks so the economic models are all viable. What happens 10-20 years from now when the roving eye of economic development has moved onto other sectors leaving the economics of ad supported saas products non viable. I fully trust Google and Facebook, but if they were to ever be liquidated / sold in pieces I dont know if my data will end up in safe hands.
This is a legit concern - there's a long history of organizations doing unscrupulous things with their data & IP when their actual business goes south. (SCO is perhaps the best example.) However, these are usually more self-limiting nuisances than long-term problems. If the business is going south, then it means the organization's actual power is declining, and this limits the damage they can do with their data. They're quite capable of making a lot of noise and annoying a lot of people, but they'd then lack the power to deal with the inevitable blowback.
What would happen if Google goes under in 30 years and sells all the data it's accumulated on all Americans? Let's say they sell it to a worst-case buyer, someone who explicitly uses it for blackmail & extortion. If they do this on a small scale, then by definition it's on a small scale, they can't make any money off it, and they get shut down legally when they pick on the wrong journalist or wealthy individual. (They're in a catch-22 when picking targets: if they pick poor, powerless people, there's no money they can extract from them, while if they pick fat wealthy targets they'll probably get fought hard legally.) If they do it on a large-scale, the public outcry will get laws passed faster than you can say "re-election", and they'll get shut down by Congress/lawsuits. Either one is a no-win for the buyer.
A totalitarian government is more worrying, but the government already has all your personal data anyway.
The other issue worth thinking about is that we are in the midst of the golden age of building networks so the economic models are all viable. What happens 10-20 years from now when the roving eye of economic development has moved onto other sectors leaving the economics of ad supported saas products non viable. I fully trust Google and Facebook, but if they were to ever be liquidated / sold in pieces I dont know if my data will end up in safe hands.