This miniLED backlight has 2596 zones. A microLED would require more than the square of that. Each of those individual zones could be subdivided into 2596 zones, and you’d still only be 40% of the way to enough total subpixels.
Huh? Why are you suggesting they’d need more zones? MicroLED doesn’t use backlight zones at all, being emissive.
Samsung is already selling 110 inch (?) and 80-something inch microLED TVs. They’re expensive but so was OLED and this shows they are fully-capable of doing it.