Some more details about AMD's future Greenland GPU were uncovered by FUD Zilla. This is to be the successor to the upcoming Radeon R9 390 "Fiji" series, it will reportedly be made on a 14nm process but FUD Zilla thinks it won't be a radically new core. The main focus seems to be on bringing more performance per Watt to market and these cards are rumored to get HBM2, which offers double the bandwidth of the HBM that will be found on the upcoming Radeon R9 390 series.
Our early information is that Greenland will be made in GlobalFoundries / Samsung's 14nm manufacturing process and it is not clear if AMD will stay loyal to TSMC for its GPUs and use its 16nm manufacturing process. Korea Times thinks that Nvidia might go after Samsung's 14nm instead of 16nm TSMC manufacturing process for its next generation GPUs, but we are not convinced.
As always, take this with a grain of salt as this is speculation about products that are likely still more than a year away from us.