Why have servers at all? For a couple of dollars more, you could equip those boards with an ethernet port and a small ARM processor running linux, with a ready-to-go firmware preinstalled, which would be configured through a web interface. Or possibly a backplane with the ARM processor and ethernet, which has a couple of slots for crypto slave boards containing the ASICs.
I like this idea, however maybe it's a case of walking before you run? Surely the flexibility of PCIe makes it useful in may cases, and adapting that to an all-in-one arm/linux unit is a small (and logical) next step.
I know I have two computers with spare PCIe slots that I'd use to start with, test it out, make sure it all works well. Unless the arm/linux all-in-one miner is cheaper (by some measure)...
I think that not everyone who would consider buying an ASIC miner will want to have a dedicated machine for it - just like today not everyone has a dedicated GPU mining rig.