The company announced Zen+ cores in 12nm that are expected to ship by early Q2 and replace the current Ryzen 7 stack, but the fact that the one after that is finished, brings a degree of certainty that we might see the Zen 2 designs next year.
This is when 7nm becomes a bit more mature and companies like Apple, Qualcomm and Samsung will help in the process. They will drive millions of mobile chips through the fabs and help the AMDs and Nvidias of the world refine the yields for higher complexity and bigger chips such as GPUs and CPUs.
Remember, Snapdragon 835 has around three billion transistors while AMD Ryzen 7 is likely to have 4.8 billion, Nvidia Volta has 21billion transistors and it is much harder to manufacture. Both Ryzen 7 and Volta GPU are significantly bigger chips and harder to manufacture too.
The Zen 2 design is complete and it improves on the original Zen core in Multiple Dimensions. We haven't got any more details than that, but it is too early to talk about a chip that comes in 2019 while you still have a Zen+ that is just around the corner.
The question remains if the Zen 3 might actually be more than Zen+ version of Zen 2 or it will be a real new deal. There is a big chance that this will be a second generation 7nm with a modified architecture but again, too early to get a confirmation on that. It would make sense as this is a good way to get a performance gains on the same manufacturing process. Zen 3 is according to AMD, on track but we don’t know that that really means.
A X86 leadership roadmap puts Zen 3 behind Zen 2 and right before 2020, but this is not a confirmation of any kind. Lisa Su last year showed a roadmap with Zen, Zen 2 and Zen 3, and all the sudden in 2018 they launched a Zen +, something that wasn’t on the roadmap, at least not on the official one.
AMD wanted to hide its cards against the competition but Intel has yet to launch its 10nm solution, and it is now more than two years late. The sad part for intel is that Qualcomm might be the first even 10nm SoC to ship in a PC and the official launch is just weeks away.