SD cards are everywhere, and are regularly used on smartphones and cameras in which the read and write speed is vital.
Now SanDisk, part of Western Digital, has shown what could be a new generation of SD cards that would make use of the PCIe interface, and its first prototype is really promising: it reaches 880 MB/s in reading and 430 MB/s in writing.
The system shown by WD at the Mobile World Congress takes advantage of technologies that have long been used in SSDs. Thus, its development makes use of an M.2 to SD adapter, and the card makes use of the same pin arrangement as SD UHS-II/III cards to create that PCIe 3.0 x1 interface with the system (via a mechanical adapter) and probably standard PCIe voltage with a converter.
Those responsible for this solution clarify that their idea is not part of SD standards at the moment, and therefore could take a long time to reach the market, but the idea seems to be attracting the interest of storage solution manufacturers that could apply it to devices external.
The SD Card Association that governs these specifications is already in fact initiating work to create that PCIe SD/micro SD standard. The performance of these cards has grown dramatically, from 54-104 MB/s of the UHS-I specification to the theoretical 624 MB/s of the full duplex version of the UHS-III. With PCIe 3.0/3.1 SD cards, performance could reach theoretical maximums of 985 MB/s .
As explained in Anandtech, the problem is not that these specifications are available, but that the manufacturers adopt them: the manufacturers of smartphones do not seem interested in supporting UHS-II or UHS-III specifications, even though microSD storage with this standard I would gain many integers for photographic applications and especially for video recording.
It seems therefore that it will take some time to see how these options even end up in our DSLR cameras – only the high-end ones take advantage of the UHS-II specification, as does the recent Sony A7 III for example-, and even more in other devices such as our smartphones.