Ain't gonna happen. Not for consumers. PCIe 5.0 is more power-hungry and costly to implement. It might carry other limitations, as well. Moreover, there's not a strong need for more bandwidth, in the mainstream/consumer segment. And, according to this, Comet Lake-S (mainstream CPU for 2020) will still be PCIe 3.0.
https://www.tomshardware.com/news/intel-comet-lake_s-early-impressions-amd-ryzen-3000,40260.html
However, it
is on their Server roadmap for 2021, while Ice Lake servers are slated to get PCIe 4.0 in Q2 of 2020.
This argument makes no sense to me. PCIe is fully forward-and-backward compatible. If you have a PCIe 3.0 peripheral, you can still use it in your Ryzen 3k X570 board! Likewise, there's no downside in buying (or a company building) a PCIe 4.0 SSD, since it'll still work in PCIe 5.0 boards. And, for companies, I'd hazard a guess that they'd learn a few things in building PCIe 4.0 devices that would carry-over to PCIe 5.0, easing the transition relative to jumping straight from PCIe 3.0 to 5.0.
In fact, the only case I can see for having PCIe 5.0 in consumer devices would be if you could reap some cost savings by cutting lane counts. However, the problem you'll run into is that people have x16 PCIe 3.0 GPUs and x4 NVMe PCIe 3.0 SSDs that they'll want to carry forward to any new motherboard, and they won't want to lose any of those lanes. So, unless a mobo somehow has an additional set of lower-speed lanes that only become active if the higher-speed lanes drop back, there's no real cost savings in it. And, for consumers, PCIe speeds just aren't a big bottleneck.
Faster bus speeds are all about cloud & datacenter. For things like all-flash storage arrays, 100 & 200 Gbps networking, and AI accelerators.
That's why PCIe 5.0 came on so quick, and why PCIe 6.0 is hot on its heels.
I predict it'll be quite a while, before you see any consumer CPUs, GPUs, or SSDs with PCIe 5.0. I'd bet at least 2025.
Maybe Intel or AMD could upgrade their Southbridge connection to 5.0 before then, so they can cut back on direct-connected CPU lanes (and I'm really looking at AMD, here), but not for their GPU slots.