Possible alternative: Raspberry Pi + Modem

That is true, but the more you centralize, the more dangerous that control system becomes. With the virtual datacenter you have the same system configuring the switches as is configuring the servers.

As I say, it's nice for highly dynamic environments, but I question the value of it for production networks.

There's also the question of if the dynamically configured switches are going to create unexpected bottlenecks. not a problem on a small network, but a serious concern on a large one.