Personally, I can't get too exercised about the possibility. My claustrophobia is manageable, but I can't see the windows on a plane as being very helpful to those who suffer from it more. (In fact, "virtual" windows would probably be a lot larger and brighter than the wee portholes in most airliners.) Admittedly, I fly more for business than vacation, but it's been quite a while since I looked out the windows, and most times these days I don't even care where the windows are. (Except for the wing exits ...)
In terms of safety, I suspect that is very seldom an issue. If staff need to check for dangers in an emergency, some type of periscope could be added around exits without weakening the airframe.
In terms of the cost/benefit analysis, making provision for windows weakens the airframe, and making windows weakens the fuselage. Being able to decrease weight, increase, strength, and save fuel sounds like an adviseable trade-off to me.
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