Even at $1299 I don't see Apple going this low considering they sell a 27" at $1000. If they offered the same quality and options as the 27" display (usb, thunderbolt, hdmi, audio, ethernet, wifi) I would expect 2560x1440 (1440P) resolution. This TV would be brand new to a brand new market of 1440P and I would expect something like this to run $2000+ for a 50".
If it's reasonably priced, I'll probably think about grabbing one. Based on the current Thunderbolt display, if they go down that route, a 42" TV's going to cost a lot more than the market norm.
42" at the same price as the Thunderbolt, and has the same colour quality, £799 would be a very reasonable asking price.
I'll look forward to seeing how this develops.
TV. This isn't even going to be about TV. It's going to be about how Apple drinks the game console and cable set-top box milkshake.