The -8 will still need to make a tech stop since it's maximum range (around 4400 nam) with a full payload is not sufficient to make it non-stop from anywere in Asia (with the exception of Japan in the wintertime) to the West Coast.
Nonstop with a "full" payload may not be as much of a consideration as nonstop with MORE payload. To give an example, a 744 can go ICN-LAX nonstop with about 103-108 tonnes, depending on winds. The Classic can barely make ICN-ANC with the same load.
If the 748 can do ICN-LAX with 115-120 tonnes, that will be a significant improvement over the Classic, and some improvement over the 744.