This happens all the time, first with laptops, then PDAs, then Netbooks and now it's tablet devices on Android/iOS.
Well there is a simple fact, many computing applications need lots of raw CPU grunt and desktop PCs will always provide more of that per dollar/euro than anything else you can create. Yes Windows is incredibly sh1t BUT it has fueled the CPU advances because it is so %&$#?@!%&$#?@!%&$#?@!%&$#?@! (and cheap terrabyte drives and cheap memory).
Add to that fact that some things you can't or won't do on a tablet and you have the simple fact a computer on your desk or a powerful laptop is going nowhere.
Cloud based computing is just another tool in the same tool cabinet, you can't undo a bolt with a screwdriver, if you keep that analogy in mind then you will be OK. Cloud based setups are helpful but nothing you couldn't do 20 years ago by emailing yourself a copy of your XL report and just downloading the attachment when you login to your email account at your other work location. Hell that principle works on even the Commodore 64

Nothing new or revolutionary will come now until the way these devices interface to the human body become embedded IMO.