Price will come down for OLEDs, but for OEMs like Sony and Samsung, it will always be cheaper to produce an LED television in house. Even if they add dimming zones. They own the manufacturing process, so they're able to do it a lot more efficiently. That's why Samsung's top of the line 4k sets have remained competitively priced against OLEDs.
And the thing is PQ improvements going stagnant is that it really only applies to OLEDs. And while OLEDs have some inherent advantages over LEDs, those advantages aren't all encompassing. LG Display appears to have given up on improving image fidelity of its panels. Instead they're focusing on form factor gimmicks like the rollable OLED.
Sony doesn't manufacturer panels for any of its displays, LCD or OLED. Very few companies actually make their own panels, companies like Samsung, LG, and TCL, do though, and I think Sharp used to, not sure if they still do. Anyone remember the Sharp Elite LCD tv, Pioneer Kuro Elite plasma clone attempt lol.
LCD image quality improvements typically revolve around contrast ratio, that's why there's the race for more dimming zones, and more LED's. OLED while not as bright as LED is probably at a point where price matters more than improving the image quality, the image quality is arguably better than LCD already (most reviewers opinions suggest that). So where does that leave LG and OLED, make the panels more burn in resistant, improve motion, add features like hdmi 2.1, VRR etc. Who knows, maybe OLED has reached the best PQ it can output, and hopefully LCD can catch up and eat LG's forcing them to further improve OLED.