By 2015 I'll happily bet a dozen 2007 Premier Cru Margot that most of us here today will carry our desktops in our pockets. I'll bet the same that we'll be using speech for almost all of our IT interactions. The only way I can see that I'll lose the bet is if there is a groundswell of belief that wireless is bad for you. In which case it will be slower and will have to use induction touch transfer or something like that.
As to whether there are still PCs; I'm sure there will be some, just as there are mainframes today running banking... necessary, but not visible to most of us.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
