A few days ago IDC released (see here and here) a forecast according to which by 2017 87% of connected devices will be tablets and smartphones. Desktop PC sales will be down whereas tablets and smartphone sales will grow double digits.
This does not surprises me, most users do not need a full PC for browsing the web and access the few applications by now mostly “in/on the clouds” that they use. Easy of access, intuitive interfaces and great graphics are more important than the full power of a desktop PC with all possible kind of resident applications (which the user should then manage).
Security and all kinds of management should be done by the device provider, better if almost unknown to the user or with very limited user participation.
Privacy and personal information dissemination are the only issue which involves directly every user, and on this point we will need to improve quite a lot.
Obviously, work related PC requirements are different, and for this use desktop PCs will remain, albeit in reduced numbers.