The fx has 4 modules. Each module has 2 physical cores. The difference between amd and Intel is that while Intel uses resources separately per core, amd uses resources separately per module, so core pairs share. With the fx series, all the architecture is the same, so if a core fails testing, an entire module can be shut off, and you get an fx6300. If 2 separate cores fail, 2 modules can be shut down and you get an fx4300. With Intel, if a core fails there's no choice, either junk the cpu or make it an i3. Saves amd considerable amounts of capital having down steps that Intel doesn't.
If I remember right, Zen will be 20nm, skipping established architecture entirely, so while it's possible that base design might be similar, there's not much chance of a rebrand.