Tablets and whatnot

I was just reading about today's announcement of Microsoft's new slate computer. It looks pretty cool, as these things always do, but the reviews didn't seem to be overly excited by it. I'm assuming anticipation of what Apple might come out with is a part of that. But in general, I'm just curious what niche these slates or tablets or whatever you call them are going to fill. Will they replace phones or laptops? They're not as small and handy as a phone, so you can't exactly just stuff it in your pocket, but they also don't have a separate keyboard like normal laptops, meaning they're not that convenient for typing, and thus for school and/or work purposes.

Is the appearance of these machines evidence of an expectation that the idea of a keyboard is going to become obsolete? I don't think so, and I don't think that could ever happen. When it comes to typing, smartphones (such as my newly-acquired iPhone) are great for short messages, like small emails or texts, or even entering a web address, but as long as people have to produce longer bodies of text, some kind of keyboard is still going to be needed. So I'm wondering if, even despite any touch-screen keyboard slates and tablets might have, they're going to be produced, marketed, and used as nothing more than multimedia entertainment devices.

My friend J. just reminded me that some laptops already have this feature, allowing you to write directly on the screen. But these are still laptops, allowing users to have all the traditional typing functionality you need for producing anything more than a quick message. I guess the best possibility for tablets to be useful for work is if they incorporate a really good note function that can read your notes and handwriting, or even just save them as you enter them without having to convert them to Times New Roman. But I don't know if they offer that, so I'm still wondering what niche tablets that are nothing more than tablets will fill.