The SDA (SD Association) recently announced the specifications of SD Express 8.0 and it is about to set a new benchmark for memory cards. As per the announcement it will do data transfer at speeds up to 4GB per second. The SD8.0 spec is built on the PCIe 4.0 standard and uses NVM Express (NVMe) technology.
Just like CF Express Cards, SD Express 8.0 can deliver either up to 2GB per sec with PCIe 4.0 over single lane or 2GB per sec per lane up to 4GB per sec using 2 lanes.
The speed breakdown is shown as under:

This announcement came when SDA is celebrating 20th Anniversary and 2 years after they launched SD7.0 and it does mark a new era in the SD Card technology. While everyone was almost writing off SD Card technology after CF Express Card was announced but with this announcement, it is clear that the photographers are going to get multiple options available at their disposal.
In fact, announcement of SD8.0 opens up more opportunities in the removable card arena and with its backward compatibility because of its form factor.
“With SD8.0, anyone taking a slow-motion video of their surroundings or taking burst photos of an athletic event, SD Express helps capture the moments at the highest qualities,” says SD Association President Hiroyuki Sakamoto. Decoding the statement of Mr. Hiroyuki Sakamoto, you can do video capture and playback both at 4K and 8K. One can even record and playback a 360-degree videos and that is something to really flaunt about.
It is important to point out that both camera and card manufacturers haven’t yet made use of UHS-II format and now that new specs are getting launched, it is possible that the industry will skip the UHS-III technology altogether.
Another important point to note that CF Express card also shared similar speed specs using four PCIe 3.0 lanes but are currently delivering 1GB/sec speed per lane. It will be really interesting to see when CF Express Cards adopt a PCIe 4.0 interface to really add zing to the entire speed race.
All in all, one thing is certain that with this announcement by SDA, the arena has opened up and now the consumers will get more options to choose from and create their content without any buffering related glitches.
So all in all a great announcement and much improved and faster workflow for both photographers and videographers.