Ok if this report is true from wccftech.com/http://wccftech.com/gtx-1060-3gb-detailed-specs-leak/. Then there will be two gtx1060 versions.
A 3gb version and a 6gb version but just too muddy the waters the 3gb version has1152 cores vs 1280 cores on the 6gb version. Although the qouted price is $149.00 so would be in the same bracket as the 4gb RX470.