Justice, though imperfectly enacted, is always what it is. (We'll skip wondering if there is an unchanging "chairness" of which my chair is an imperfect 'enactment".) So (work with me here) our thinking about eternity "has" to have changelessness included.
When I thought of the "chairness" of your chair I thought of God's throne in Heaven (whatever that literally is). I presume that it is changeless, but that it was also created since it is a part of Heaven. I would presume that the "rooms" that are also being (have been) prepared for us will also never decay. However, when we receive our glorified bodies will our "rooms" be changeless? That would mean never being able to pick up anything, etc., etc. I'm not sure if it really works like that. Throw in the human soul as a kicker. :)
So, we have created things that will exist from the time of their creation to eternity forward, some of which even in Heaven might change (and some maybe not), and then we have God Himself, never created and never changing, but I would say not static either. So yes, if we mean "eternal" eternity then changelessness is definitely noteworthy and part of the mix, but I don't think it ends there.
But the Revelation about "one" [concerning, God is one and a Trinity at the same time] may provide us with kind of a clue, at which we can only marvel: that as oneness seems to have "room" for plurality, so changeless eternity may have room for something kinda sorta like Dynamism. That's all I can do right now.
OK, that's cool. You're obviously willing to think about it, so what more can anyone ask? :)
I think both of you (Forest Keeper and Mad Dawg) need to define your terms before jumping head-first into these discussions on eternity and changlessness.