Well, I'm building one myself right now. I bought a 5th gen iPod video (2006 enhanced version) and ordered a new faceplate to get rid of any scratches, a CF card to ZIF adapter, and a 64GB CF card. It had the stock 80GB HDD, but I wanted flash for speed and durability.
As to if Apple would ever make one, unlikely. If they did it would be the nano, or a refreshed classic using flash, something like 64GB/128GB models or so I would think. But I doubt that would be on the horizon.
You can get them on eBay pre made fairly easily. Or make your own like I did.
This also applies to the iPod mini, it's smaller but has a monochrome display, so no video.
Nope. Never going to happen. That's what the iPod Classic is for but that's aging and I wouldn't recommend you buy it. The future is streaming music.
It seems that way, but as someone who works out in the midwest, there are plenty of areas without any cell signal, or if there is, it's voice only, eg. no 3G/LTE. And I'm on Verizon. Also lots of people have data caps now too, or simply want to hold their entire library. There is still enough demand for the classic that they haven't stopped selling it, even if it hasn't seen updates for 5 years.
I bought the current 160GB iPod classic just a few weeks ago, and it's been wonderful. I use it in the car a lot of the time and the click wheel is so much easier to use than a touch screen when you're driving. You don't have to look down to change songs. Just press the button. With more cars getting USB inputs and bluetooth I'm sure that will start going away too, but there's plenty who don't have that. My tundra has a good ol' aux in, and I'm perfectly happy with that.
But I agree, likely never going to happen.