Re: What sort of motherboard slot?
M.2 and NVMe are two aspects of a newer drive standard designed for solid-state and portable (as in laptop) applications. NVMe is the slot spec, M.2 is the physical device spec. Since you mention a five-year cycle, you probably don't have a capable motherboard, and that's no big shakes since the standard's only been around a few years now.
To summarize, solid state drives don't need big honking housings (M.2 drives as you can see are comparatively tiny, the numbers used in the spec describe sizes) nor do they need interfaces designed for slow spinning rust (good NVMe drives hook direct to the PCI Express bus, addressing them more as memory than as drives). End result, a highly efficient drive bus you can still squeeze into a laptop.
But who's to say laptops have to have all the fun? Servers caught on to the idea first because space is also a premium to them; smaller drives mean you can cram in more of them or give the case more room to breathe (being solid-state with higher reliability helps, too), and with two legs of the computer triangle already down, endpoint PC makers realized the future is PCIe-attached SSDs: likely followed by SSDs as RAM (this is probably waiting on post-DRAM tech: a while longer right now). Since the wiring is PCIe-compatible, it doesn't take much work to shift some lanes into an NVMe slot or two. If you have a spare 4x PCIe slot, you can fit a bridge card that lets you take an NVMe drive as a stopgap, but future computers will already have the slots on board the way SATA ports were included in the past.