Now that Server.app is dead, I’m looking at a few hardware upgrade paths.
There are some great highly performant, low power, OpenBSD-based server options out there, like this fanless atom system:
This solution could handle the PF firewall, DHCP, DNS, Apache, OpenVPN, all at multi Gb/s on the LAN, drawing maybe 10 Watts, and at a tiny fraction (perhaps a fifth) of the expected cost of the new Mac Pro’s promised this year.
I was planning on a new MP before the demise of Server.app, and I’d still prefer an all-Apple vertically integrated solution to mitigate the multiplatform maintenance, but this looks tough without Server.app. The replacement for Mail/Calendar/Contacts is a tbd, but could also be done on a micro if a NAS is added to the build.
An atom SoC also has the advantage of not having services withdrawn or unstable once it’s been configured.