Good article comparing strenghts and weaknesse of future possible types of memory:
https://semiengineering.com/new-memories-and-architectures-ahead/
"The list of new memories vying for attention include Phase-Change memory (PCM), Ferroelectric RAM (FeRAM), Magneto-resistive RAM (MRAM), Resistive RAM (RRAM or ReRAM), spin-transfer torque RAM (STT-RAM), Conductive Bridging RAM (CBRAM) and Oxide-based resistive memory (OxRAM)."
As the article states, the IoT market will be hundgry for cheap memory with low power consumption hopefully that will help bring costs down. (Talking about prices, I know ReRAM is silicon oxyde based and could be produced by the same factories as now with the same type of material, so they wouldn't have to change everything to be able to produce that kind of memory, I'm not sure about others though).