The hot-swappable drives slide in through the card’s rear I/O panel.
External enclosures are another option, but they come with their own set of limitations.
No word yet on availability for the M.2 Xpander-Aero Slider Gen5.

According to a report from KitGuru, the expansion card will come bundled with future high-end MEG motherboards.
MSI could be on to something with the sliding concept.
Would you have any use for a PCIe SSD card like this?
Image credit: Future