I think a TL;DR on my reply above:

I think the difference in privacy between identity(ephemeral(x)) and ephemeral(identity(x)) is not significant. It's more honest to tell people that our product offers only content privacy not meta-data privacy unless we are truly implementing strong countermeasures against tracking by ISPs or others that can pervasively sniff the net. Just nixing the identity key visibility is not a strong countermeasure for the reasons I described.