If we look at the evolution to 400G by Cisco we can see how they have been motivated to find ways to improve the optical side. As I previously posted they expect to be delivering 400G optical modules (pluggable) in 2020. What I find interesting is that Cisco is quoting world class coupling loss at less than 1dB. The Luxtera development work with TSMC never achieve that level of improvement. Waveguide loss was reported as 1.9dB/cm and coupler loss was 2.2dB. You can draw your own conclusions as to  how  Cisco expects to  achieve cost savings along with that level  of  coupling improvement.

https://blogs.cisco.com/sp/optics-in-the-data-center-powering-ever-increasing-capacity-demands