I think there are two factors in play here at present.
First, if you use your BM5/BS5 "correctly" and have it communicate with the B&O server and only approved N.Radio channels as designed, then I see the risk as very very small indeed. If your going to be unwise and use your BM5 for surfing the web, then after 5 years your simply asking for trouble. Use your standard PC for that. It will be better set-uop with mouse, keyboard etc....
The Second factor is if B&O are going to use a standard digital platform with regular updates for most of their new PC-based products, then AV guards will be commonplace and it is highly likely that once you buy a product, it will be protected for the life of that product.
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