PCs will never die, but the current trend we are currently experiencing is more of a fusion of both tablet and PC form factor.
Basically, it all comes down to the question of how much computing power & performance do you really need? While there will always be those individuals that will require unlimited computing power, the average consumer has the most basic requirements. (browse the internet, check e-mail, facebook, etc.)
As devices get smaller and more powerful, more and more *consumers* will find that they just don't need that bulky desktop sitting under their desk, and given the option will choose a smaller form-factor device. Note that we are already seeing this trend in the increased sale of tablet devices.
This will eventually translate into the business sector as many corporations are already finding viable solutions to their business needs by way of tablet computers, particularly in hospitals and education, and sales professionals.
Now add remote access and virtualization technology into the mix and you now have very convenient mobile devices that can connect to remote PCs, terminal servers, and cloud-based devices like Google's Chromebook which will alter the entire PC landscape.
Personally, I will always have use for a PC, but there is no denying what is happening right before our eyes (sorry for the long comment).