Here's now I see it:
For myself, I'll settle for nothing less than the best, 9.7" retina display iPad. I rely on my iPad, I use it daily and absolutely love it.
That said, at $249-299, I'll buy a mini to keep around the house for sharing and for e-reading. It's a better size for that. I'll also likely buy one for my Mom and Dad as gifts. My Dad is too stubborn to buy one himself and my Mom is pretty much computer illiterate. This would be the only thing that might work for her, but at $500+ I'm not ready to risk a gift that ends up sitting around doing nothing.
At $199, I'll probably end up gifting a half a dozen in the first year alone. Even if it's a Mini, an iPad is a pretty cool gift and at $199 I can afford to give a bunch of 'em.
My guess is we'll see them as WiFi only devices, starting with 8GB of storage at $199, 16GB at $299 and so on.
The only reason for Apple to push this product to market is to take the tablet market by the throat. Nexus 7 is $199 and is apparently a decent quality product. Kindle Fire, while not a true tablet, is not a bad product and is also $199. It's also going to be updated soon.
The other area of importance is Windows 8 tablets. Those manufacturers, Microsoft included, are not attacking the 7", sub $299 tablet market. Windows appeals to the average person who is generally basing his or her buying decisions on price. If the MS Surface is any indication, the Win 8 ARM tablets will be $399 and up. If a $199-299 iPad, that already has a great reputation and a massive amount of applications available is out there, Win 8 tablets will be DOA. I think Apple wants to win the mobile OS war. Great quality isn't enough. You have to hit the mass market price points to do that.