I watched a presentation with Microsoft Nvidia and Ayar Labs last week. I believe this is why Poet will be successful, everything Suresh has done has been to make the interposer in a Wafer Level CMOS Process.

That will be how low cost will win for Poet but also because they're integrating lasers and using CWDM to multiplex the signal in an Fr4 format (the most popular for large volume applications.