Looking at those speakers I can understand why you like the looks of them. I hope you have listened to them before deciding on them.
AirPlay should be around for a long time. And even if Apple updates the AirPlay protocol , it should still be compatible with the the current AirPlay speakers.
And worst case there is a line in you can use according to the web page you linked so at the least the speakers will still be useable even if something (which I doubt) happens to AirPlay.
Ya I've listened to them a few times and the quality is stunning. Like you said, it's very reassuring to know there is a wired possibility, but with something that cool looking, I love it not plugged into a device.
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1. I suspect that most people that believe this is a lot of money to spend on speakers have never heard great home speakers.
2. The OP wants to keep the speakers for 10+ years. Ironically, most of the people commenting on this post will buy 5 $700 phones during that same time period (yes, the phone costs you that much whether you're paying the amount outright or subsidized over time). At the end of the 10 years you will have an outdated phone and great speakers will still sound great.
That's a wonderful point, and a great way of helping me decide to buy it
Like mentioned, smartphone technology moves much faster than speaker technology. You never see people using first gen iPhones, and those are 6 years old. My grandfather still has Bang & Olufsen speakers that are 20+ years old. That's why if I spend all that money, I want to make sure not only it will work for a long time, but that all the features (such as AirPlay) will still be a possibility.