I certainly don't believe they will get close enough to OLED in black level handling. Will it be better than current LCDs? Sure, that's why the reference displays use such a setup, since they don't need to care about viewing angles, power consumption, display thickness and aesthetics, etc.
Making and aligning two LCD panels won't make LCD cheaper, and won't help overall brightness, so they may have to increase the backlight brightness to compensate so then power consumption goes up.
So interesting idea, and I can see why the pro displays use such a setup for high brightness reference setups, but for consumer TVs, it doesn't look sensible to me.
If somehow it did start to impact LG (and I don't think it will), they could start pushing their wallpaper and rollable models a bit more, which are certainly things and LCD will not be able to match.
Sony XBR55A1E, Marantz SR6012, Benq W7000, Oppo BDP-93, PSB Image T5/C5/B4/Subseries 200