Another unit that I found that can connect via I2S is the Sonore Rendu PCM/DSD Network Audio Player with Ethernet Input and SPDIF/HDMI i2s Output.
This unit sounds very intriguing to me since it can connect to the network via Ethernet and access JRiver via JRemote on my office PC.
Another unit that I discovered that will have IS2 is the future PS Audio External Bridge that they will build after the PSAudio Internal Bridge II is released.