With the rumored launch of the next CPU generation "Kaby Lake" right ahead of us, we should also see quad-core ULV processors from Intel for the first time. There seem to be 15 and 18-Watt models with four cores and Intel HD Graphics GPU.
http://www.notebookcheck.net/Intel-Kaby-Lake-Quad-Core-ULV-Processors-in-2017.172188.0.html