To give a answer to the question: "What will the device of the choice of the future be ?"
I think smart TV's and TV-boxes are something to keep a eye on as well. TV's are the biggest screen in most houses and can do many things. ( i'm working on porting Steemit apps to Android TV (and Android phones and tablets) it will bring more Steem to a variety of Android devices.)
Preview :
The only technology that could make the others obsolete is something like a augmented reality lens or glasses, then we maybe stop using the phones and TV and we would not need those devices any more.
Good point virtual reality may be the future.
I disagree since even cheap TV can become smart with TV Box or mini PC such as Raspberry PI. Unless smart TV become cheaper in few years later.