Tim Cook uses his iPad for 80% of his work
Apple has often said that the iPad can be a replacement for quite a lot of the things you might need to do on a daily basis. Some people still need a more full featured computer for advanced tasks, like hardcore gaming or video production, but most things can be handled on a tablet. And, Tim Cook appears to be proving that true by doing 80% of his work on an iPad.
Or, maybe Cook is just claiming that to be true because Apple and IBM are trying to push iOS devices for enterprise use. It is certainly a good sound bite when trying to sell iPads to enterprise to be able to say that the head of the world's most valuable company does 80% of his work on an iPad. Overall, it isn't all that hard to believe either.
Whether or not you can trade in your Mac or PC for a tablet is really a personal decision. Or, it may even be something of a leap of faith. You may assume that you absolutely need to have a traditional PC, but may find that you can get by with just a mobile device, if you have to.