The first desktop and laptop DDR5 RAM modules are now expected to be released at some point in 2020, as JEDEC has not yet finalized the hardware specs for the DDR5 standard. What we know for sure about the DDR5 RAM is that it will feature at least double the bandwidth, 4800 MT/s and later on 6400 MT/s speeds, plus independent 40-bit channels per module.
https://www.notebookcheck.net/DDR5-RAM-production-postponed-for-end-of-2019.338878.0.html
Why would they bother releasing DDR5 when DDR4 is crazy overpriced and they are making a killing? The delay is most likely because they can milk DDR4 for yet another year before prices become competitive enough.
RAM prices have dropped significantly over the past few months. The prices were so high because of the lack of supply.
Two years later, and still no DDR5. :-\