I've been evangelizing faster Ethernet for a year or so now. In the years to come, we will slowly transition to faster Ethernet as 1 Gbps is getting out of fashion.  There's a move coming though, Realtek will be releasing three new 2.5 Gbps Base-T Ethernet controllers.

While Quantia already offers up-to 10 Gbit/s solutions, steps are always small in the world of mainstream technology. And yeah, 2.5 Gbps in theory roughly 325 MB/sec in PHYs that is going to make its way into motherboards. Basically, in the initial launch wave, you're going to notice the RTL8125, RTL8156, and RTL8226. The RTL8125 is the chip to get and will be embedded onto motherboards and is based on a PCI-Express 2.0 x1 host (has 5 Gbps bandwidth, not to confuse with the 2.5 Gbps link).

The RTL8156 is designed for USB dongles over USB  3.1 gen 1 (5 Gbps) and then the RTL8226 is a chip that will end up in routers and switches. We think you'll see the new 2.5Gbps implementations real soon, even on some new Z390 motherboards. The standard is obviously backward compatible at 1 Gbps / 100 / 10. For 2.5 Gbps to work, obviously your network infrastructure will need to be updated as well, that means your switches. Cabling will be fine though, even CAT5e can easily reach 5 Gbps.

If you like to have a taste of what super-fast ethernet brings to the table, might I steer you to these two reviews I made (here),(here)?

2.5 Gbps Ethernet going Mainstream? Realtek launching RTL8125 mobo chip