I think "damnation" is generally understood as God's condemnation of our failure to draw near to God. I think that condemnation is generally understood to be eternal.
Athanasius was pushing hard to make a point with what he believed was true and what was not. He was drawing some pretty heavy lines in the sand, partly, I believe, in order to make his statements authoritative. "Acceptance of the Trinity" (as forumulated) was seen, at that time, as the core doctrine of the Church. Today, most authorities tend to point out, rather than dictate, doctrine. Even the RCC has relaxed its stance somewhat. While the doctrine (or some form of it) remains a core doctrine for the Apostolic churches, the need to "enforce" the doctrine has relaxed.