I'm glad you noticed this because this is exactly what I think they should do. I'm currently playing on Selos EQ progression server and it's actually a ton of fun.
Can you imagine how cool it would be to have a progression server that goes to wrath and then time locks in that era? Or having a progression server that goes from classic to current content over a year or two? It would add a new flavor to the game and allow you to continue to play the same game but in a different way. And I really don't see this detracting from live wow in any way.
I think DBG stated that about 1/3 of their total revenue comes from progression servers such as these so they could potentially inject a ton of money into wow again which would be good for everyone.