54-40, not sure about the path of your sunshine, but I'll try "non tech"
First off, John posted a couple of tech reminder pieces worth reading this morning.
So, do you know that song "too sexy for my clothes?" Well, that's POET's problem with this issue. The interposer is so damn fast and simple that the optical engines need parts that can keep up. One of those things, at the moment is the silicon based modulators. Suresh says "they have not been mature". That means they suck 'cause they can't keep up. So POET is investigating and investing in other design/ base element modulators to find the perfect match.
Is it logistical? Well, it means that someone on the component side needs to step up to produce a modulator/laser package that Suresh is satisfied with. Is it fundamnetal? No, keep in mind that the 400g transmit side works, just not fast enough right now.
What is important, I think by Suresh's words "the roadmap becomes very clean" is saying this step is important to the NA and European side of the roadmap. DO they have the piece they need? Suresh's enthusiasm says to me they are close.
Keep in mind the 100 and 200 side with the JV side in China is on track.
IMO, of course