If They CAN Watch You, They WILL Watch You
The concept of eternal flight aircraft is really INCREDIBLY cool:
Just from a geek standpoint, it's fabulous. That there could be some flimsy piece of technology that's hanging around at 90,000ft, NEVER has to land, and is remote controlled....I love it.
Remember that only the government would do something like this. And the government CAN NOT BE TRUSTED! This is beyond the range of visibility. You WOULD NOT KNOW if these things were flying around at any given moment in time. You WOULD NOT KNOW what kind of surveillance setup these things had.
THEY WILL BE ABLE TO WATCH YOU!! And it will cost them less money, and it will be for longer periods of time.
Do we care? Well, that's entirely up to the individual...It also depends on what kind of legislation surrounds these things.
Could they just hover above a city monitoring traffic? Send tickets to whatever car owners have cars that speed or merge poorly? I doubt it, but it is feasible. Could cities use these to track criminals during car chases? Possible. Somewhat useful, I would guess.
How about detecting radiation around cities? That's a pretty usefull thing. It would be very nice to know if any suitcase sized pockets of radiation entered Boston...
Just remember, that's the justification they will use when they try to bring these over your city. They'll say it's for your protection...
In the immortal words of Mr. Cobain, "Just because you're paranoid, doesn't mean they're not after you"