It has been a few years since I retired so I don't know if carrier grade ethernet has actually appeared yet. I worked in transmission and one of the things that was very noticeable as ethernet bearers replaced TDM was the limited nature of ethernet fail over. We actually had situations were optical protection switchs were specified rather than end point protection because of their guaranteed 50ms switchover. This despite it introducing a single point of failure (the protection switch) and that ops only switch on loss of signal, not signal degrade which is standard in TDM. I suspect that the intermittent nature of ethernet compared to the continues nature of TDM will prevent the implementation of the type of protection schemes used in TDM environments. Unfortunately ethernet is cheaper and even when I retired we were providing customers with 100Gbs ethernet circuits. So far as I am aware the highest specified TDM client rate is 40Gbs and this is rarely implemented.