Supply and demand boys and girls. There's a shortage of OLED, so the way to alleviate demand is to jack up the price. Econ 101. The 7s/non premium models are happening, but consumer perception will decide if the "8" is worth it.
Thats not how companies like apple work. They won't artificially bump the price to deter consumers from buying their best product. Supply and demand works in markplaces as a whole, not when a company is the entire marketplace. They will have had the price decided for a long time now and it won't be anything to do with the scarcity of OLED panels.