Webkit is missing a _lot_ of useful features. Safari not implementing something doesn't have to mean its dead. It just means iOS users will be forced to download a separate app to interact with Bluetooth devices via the web.
Do they provide such a low level API to usual mortal developers? This isn't going to be nice and comfy in terms of usability if it happens the way you describe.
I would not say it's likely to die because it's obviously false since on iOS it's the only choice but it's true that when you see the release logs of Safari, it's moving very slowly very far behind Chrome or Firefox.
