Samsung has announced [businesswire.com] the mass production of 12 Gb (1.5 GB) LPDDR4 DRAM [wikipedia.org] chips on a 20nm process. The state-of-the-art was previously 8 Gb. The new DRAM chips could enable the production of smartphones with 6 gigabytes of RAM [anandtech.com]:
The production of 12Gb chips opens up the possibility of smartphones and tablets with 6GB of RAM using a four 12Gb chip DRAM package, as well as 3GB using just two chips in a package. A 6GB package would also only take up the same amount of space as existing 3GB packages which use 6Gb chips. The new 12Gb chips also end up being very slightly more than 30% faster than their 8Gb chips, with a per-pin speed of 4266Mbps which would give 34Gbps of bandwidth over a 64bit bus. With Samsung beginning mass production of this new memory it's only a matter of time before we start to see more devices move from 2GB to 3GB and from 4GB to 6GB of RAM.
There are several phones on the market with 4 GB of RAM, such as the Oppo Find 9, Xiaomi Mi Note Pro, ASUS ZenFone 2, Sony Xperia Z4, Lenovo K80, Huawei Ascend D8, and soon, Micromax's YU5050 [indiatimes.com]. These manufacturers could use 12 Gb chips to create phones with 6 GB of faster RAM without using additional chips.