I just read a piece in MacWorld asking the question, "Can a tablet replace a notebook?". According to the article the answer is no. I propose that the question is invalid. A tablet and a notebook have different functionality and are not substitutes for one another. In fact, I believe that it is this type of thinking, i.e., one replacing the other, is responsible for the failure of tablets in the past.
You use a laptop to act as you portable desktop. Anything you can do on your desktop machine you should be able to do on your laptop. I personally have taken this concept further and simply use a laptop for everything. The only concession I make is that when I'm working at a desk I use an external keyboard and mouse. In addition, I use an external monitor in my home office.
So what is the purpose of the tablet? First consider the functionality found it today's smartphones, e.g., the iPhone. It can do email, surf the the web, manage your contacts, manage your calendar, act as your iPod, take photos, take video, do texting, and provide maps. If that isn't enough then all you need to do is visit the App Store and browse through the 100,000 apps.
What doesn't the iPhone do well? Two things come to mind - typing and surfing the web. The virtual keyboard works well but I wouldn't want to write a multiple page document with it. Common sense dictates that a laptop would serve that function much better. However, the vitual keyboard on the iPhone is great for short emails, texting and taking quick notes. That takes us to surfing the web. Now I use my iPhone constantly and I surf the web with it. However, once again, this task is better suited for a laptop because screen real estate matters. Surfing the web with the phone is great for quick inquiries but you wouldn't want to surf and read for hours.
So why should I need a device to fill the space between a laptop and a phone? Answer - You Don't. Each device serves a separate purpose and they serve them well.
Then what would a tablet do? As I have stated previously, it will act as a media pad. You will access the internet, read ebooks, read newspapers, read periodicals, look at photos and view videos. Can you do this with a laptop or an iPhone? Yes, but the form factor is wrong when you think of portability and functionality. The laptop is too big and the iPhone is to small. Hence, enters the tablet.
Will it run productivity applications, ala, iWork? I believe yes but it will run them in a cloud computing environment. The focus will be on accessing documents and making minor changes. It will not serve as your primary typing platform.
The only question is what will you use for a keyboard? I believe you will have the choice of using a virtual keyboard or a bluetooth keyboard. However, if you need a bluetooth keyboard then you are probably using the wrong device. Heavy keyboard activity should occur on a laptop.
Replacing a laptop with a tablet is like replacing your oven with a microwave. They both cook but each is suited for a particular type of cooking.