None of that really helps LCDs primary downsides of poor contrast ratio and relatively high energy consumption. Backlit displays will always inherently score worse on these metrics vs self emissive displays.
peak brightness is not contrast. If anything higher peaks mean worse contrast, even for systems with local dimming zones due to bleed between zones / gradients in display content which do not align with backlight zones.
LCDs as a transmissive display technology work by emitting a bunch of photons and then selectively filtering some out to achieve the desired color / pixel brightness. Any filtered photon is wasted energy, this is inherent to the display technology and is not limited to dark content, just exacerbated by it.
Given that, all things equal there is no way for LCD to equal the efficiency of a self emissive display, at best it's a question of when will the luminous efficiency of OLED exceed that of white/blue backlight LEDs... and honestly we're likely already at or past that point.
In terms of TV. LCD have higher peak brightness. The Sony Bravia 10 will be out soon, hopefully it will showcase the world what LCD could be.
Not to mention cheaper at larger size panel.