Multi-purpose devices ALWAYS win out in the end.
That's why we got rid of our big screen TV once we were able to stream Netflix to our 6" tablet computer.
Oh, wait...
In all seriousness, I do like multi-function devices, but the idea that multi-function trumps all is, I think, a fallacy. Unless LCD screens are going to suddenly become as glare-resistance as e-Ink, the dedicated e-Ink devices will always exist for the beach crowd, which is good for the e-Ink purists. (Cue Kindle commercial: "I paid more for these sunglasses!"
)
The bottom line is that if a multi-purpose device is going to put a single-function device out of business, it has to duplicate ALL the functions.
And even then, how many people on Mobile Read complain that tablets "distract" them from reading? I see that every day. And then there's the battery issue - people in MY corner of the world still buy dedicated MP3 players because listening to music all day on your phone will leave you with a dead battery after a few hours.
I don't see e-Ink going away any time soon as it has too many advantages over the multi-function devices. But I don't blame some guy sitting at his computer for not thinking of beaches and battery life - you tend not to notice those things until they suddenly become a major issue. And then you buy an e-Ink reader.
