I don't believe it will comes this year, but there is nothing about this that is as dramatic as your claiming. 7nm consumer products are coming this year. Navi being desined for 7nm. The X360 had one of the most advanced AMD GPUs when it released. There is nothing saying Sony will use an APU in the PS5, in fact it has been rumored for a long time that the CPU and GPU might be seperate chips.
Sony could definitely launch a PS5 with Ryzen and Navi chips this year. The CPU and GPU tech will be ready, but I don't think the production scale will be there.
Again, I don't see the point in a new generation with the available CPU, GPU, Memory, and Storge that could be built into a $500 box this year or next, and I hope this is wrong, but it is totally possible.
Sorry for my French, but Who The F&$& has been talking about using separated CPU and GPU?
That is the most stupid idea ever. If a big APU is expensive, it is still far cheaper than discreet components. The simple fact that you have to wire and encapsulate two different types of chips would add extra costs, without considering how to place them on the motherboard and m race memory banks.
The whole point of having a console insted of a PC is the extra power you can get at a lower price, smaller size and more efficient overall design.
Sony, Microsoft and Nintendo will aways use proven technologies and architectures.
I won't rule out Sony launching a PS Pro 2 this year and it can even be a beast that would smash the Xbox One X, but if they do, it will be using old tech like Polaris and Scavator.