This is also my understanding. I thought I saw some work being done
on an enhanced DXI specification, (the interface between the router and
the ATM DSU), but I think that, for the most part, not much work is
being done with ATM DSU solutions today. ATM DSUs were largely
developed as a quick-to-market solution for adding ATM functionality
to routers, without the need for new router boards. Their time has passed.
I don't think that HSSI was designed as a point solution
until ATM came along. Couching your answers in the context
of an ATM solution is presumption, or so it appears to me.