@Spectrum48k:
I suppose it's future proof - my ISP here in the UK keeps doubling my speed at no extra cost. Its going up 50Mbps to 100Mbps soon, so I'm guessing in a year or two an i3 might be ideal, although they do a J1900 Celeron too? Might check out the TDP figures and see what's the best fit.
Tried looking for just a motherboard with dual intel LAN which ARE about, ie the H270N and H270M from Asrock and Gigabyte, but then you need to find a low TDP processor and looking through the latest Skylake and Kaby Lake, they all seem to start at 35W. Why did Intel abandon the Atom? I wonder how long til we see an ARM based board with dual LAN, pushing 100Mbps?
In 10 years it'll still be overkill. The specs in my sig were running 2 x 1Gb LAN links, and 2 x 100Mb WAN links. A persistent SSL site-to-site VPN tunnel, VPN connections, several web servers, and dozens of users behind it. Several pfSense packages and some creative policies/routing too. The CPU never went above 15% at any time. And it was a dual-core CPU.