the $100 price tag on 1tb drive is A) the consumer retail price, wholesale in the volumes apple would want would cut that cost drastically. and B) with 3tb drives out later this year that will cause the price to drop again dramatically on 1tb drives especially now there making there way into the 2.5" form factor as well as the 3.5" form factor.
with apple now making there own chips that also means that overall component costs will be lower as they could make the processors and graphics etc in house and they already have staff to do the software so thats been paid or already.
requiring a local nas or external drive for storage is something apple just wouldn't do. they like there products to look clean and uncluttered which is what i like them for. so to have to have an extra box just to store the media is silly. have it as an option though to expand internal storage i think would be fine.
Apple of all companies is not going to buy hard drives at wholesale and then sell them to you at that wholesale price. You'll still be paying basically retail price for any hard drive the ATV comes with. For instance, look at the difference in price between different sized drives in the iphone, ipad, and ipod lines. When nothing else changes but the storage size, you still pay retail price on the difference. Or just try adding a larger hard drive to a macbook and see if you'll be paying wholesale prices or not on the upgrade.
The reality is the hard drive is a large percentage of the price of the device and needlessly so.
You can't do something about making it handle HD video better without using more expensive components and software development. To think you could bump up the hard drive as well and keep the price down is just unreasonable. It has to be cheaper than what it is already to appeal to the masses and I can't see anything else that can be cut back or cut out entirely to make that $99-$149 price happen.
As for an external hard drive or NAS being "required" in that scenario that simply is not so. Many people with ATVs just stream everything from their Mac anyway right now so it is not required. With the option of streaming from the new datacenter you might not even need a Mac to sync with let alone an internal hard drive.
In fact, you would have the OPTION of adding your own local hard drive space whether externally attached or through NAS but it certainly wouldn't have to be required.
TV must be thinner and/or smaller, how about use the OS X network underpinnings inside so that storage can be any size via NAS? That could yield a cheaper 
