Samsung is about to find out that Dolby Vision and price matter more than a mild technical superiority in image. Remember that when the LG 'EX' models come brighter they'll need to use the white subpixel less so they'll have an expanded gamut as well narrowing the difference. Meanwhile consumers are pretty much all in on Dolby Vision and a better price plus a feature they demand is likely to keep the ball heavily in LG's court.
Lastly remember the quantity of available QD OLED sets is going to be very limited. That will initially boost demand when people hear "out of stock" thinking it must be super popular. But remember this impacts warranty claims too. Some people getting bad screens out of the box are having to wait months for a restock to come their way. These factors are not going to make for a happy consumer base. But for Samsung it is what it is. They foolishly bet on avoiding Dolby Vision, and if you recall the Blu Ray vs HD DVD controversy from a few decades ago you'll know that the loser is forgotten in history. In the end even if QD OLED is superior (remember betamax?), quantity, better price and "90% as good" will win with superior sales numbers, superior customer base, and a key feature like Dolby Vision sealing the deal.