Tablets tend to suck for creation. There are limited exceptions, but for the most part a mouse n' keyboard, and a screen without your fingers in the way, are what you want for creating things. This includes software, of course, but also more mundane business things like financial spreadsheets, e-mails, and so on. It applies to other creative pursuits such as writing, video editing, and so on.
Basically tablets are reasonably good if you want to consume content. You can read a book, surf the web, etc with ease on a tablet. However when you start to talk creation, they are not as good. They can do in a pinch, but much better to have a real keyboard and larger screen.
What we are actually seeing is not desktops and laptops "dying" but rather maturing. The market is more or less done growing. However that doesn't mean it is going away. The two states are not "growth" and "death". Rather it can be stable.
We've already seen this in things like mainframes. Desktops didn't kill off mainframes. You can still buy them, and people do. There are more of them now then when there were only mainframes. However it is a mature market. There aren't many organizations that want one, and you don't replace them that often. So there's no growth, but it isn't dead by any means.
That's what is happening with desktops. Go in to a business, have a look around, they have not tossed all their computers and started playing with tablets and phones. There is a computer on every desk practically. However, as noted, there is a computer on every desk. They've got their computers. They buy for replacement now largely, not to increase the numbers.
The only people who think desktops/laptops are going to "die" are either kids who just play on their smart phone and don't do productive work with a computer, or idiot tech journalists.