Even FALD does switch off zones when there is nothing in the whole zone. Both do the exact same thing, just on different scales. Even LG calls their OLED as 'pixel dimming' but it can switch them off.
Yes, but each pixel is a zone and essentially it's the same thing. Just OLED can do it on a per-pixel level due to them being emissive. It's still a FALD, not a FALD LCD though.
Dual-layer TVs are coming from Hisense this year. Not sure if they'll launch in India after the govt. gave them the finger last year by import bans, but they're definitely coming.
It will be expensive though. The dual-layer nature of LCD requires a stronger backlight and obviously, you have 2 LCD layers instead of 1, so there's extra cost there too. That's why only used in professional reference monitors till now.
Also, it might be bad for gaming as 2 displays are synced up, so there will be a latency hit.