Ok, I think you included two question at once.
First, I don’t think there is a download for the pre-compiled version coming, at least I haven’t heard anything in direction. You would need to download UE4 and wait for 4.8 to be released to download the “open” version for the editor.
Second, the demo ran on a GTX Titan X with 30fps. It doesn’t use LODs or any other optimizations and is laid out for best fidelity, so I would assume that you could start it but run it with, what, 2fps? Don’t forget we are talking about a tech demo which is supposed to show the boundaries of the engine with the current top hardware. I wished I could run it too, but I also own a GTX970. (I wished I could afford even better hardware to deliver appropriate fidelity to extreme-end PCs as well, but will have to wait.)
I think Epic will include optimizations for us when they release it, otherwise a lot of people will have problems running the demo, but I’m not sure.
Greetings,
Dakraid