I imagine a purely text-based terminal set up running on a specially crafted host OS/VM that does the text-to-speech would be a fantastic solution. You can browse the web, email, twitter! I'm not sure how CLI browsers handle JS?
If this existed would there any good reason to be using a GUI at all (for a Visually Impaired Person)?
I think Emacspeak is close to what your talking about.
http://emacspeak.sourceforge.net/
The reason I don't use it is because I could never get it to work quite right so just continued using Windows. It's a lot easier to use Windows, Eclipse, Outlook, Office, etc even if it is somewhat less productive then Emacspeak would be. The amount of time I'd have to spend working around how to integrate with my co-workers Windows based setups if I used Linux with no GUI makes it a non-starter.
Mainly if you are working with others, this approach would fall on its face rather quickly. People actually do this, doing all their work using emacs modes and Emacspeak. It can be done, but in this day and age it is not the most elegant solution especially with web 2.0-based websites
The only command-line screenreader-compatible browser I know of that also supports JavaScript is edbrowse, which is not so bad to use if you’re already familiar with ed.
If this existed would there any good reason to be using a GUI at all (for a Visually Impaired Person)?