Desktops may still be around for a bit longer, but ultimately are doomed, except for very specific niche markets. I project about 4 years, so 2017 is probably the end. I wish it were not so, but it is inevitable. Consumers are now driving the market, and they don't want a desktop.
Desktops are: Huge energy hogs - strike 1. Slow to boot vs. tablet - strike 2. Not mobile - strike 3. All these factoids added up means death knell for 90% of users.

What will replace the Desktop? Not a tablet, not a laptop - it will be a combination of the Cloud and/or home private cloud storage, plus a device that can access the cloud. Take a look at the new NAS devices on the market today - they all have private cloud capability. Why carry all your data with you on your device? With private cloud, you only grab what you need. More to the point, all the new NAS boxes have streaming capability - and nearly every consumer entertainment device has streaming built-in. That is the future, like it or not. If you don't like it, you'll have to build your own desktop, provided you can get the parts.