If I remember correctly, SE said that they were making new avatars, after Odin and Alexander came out. Who knows what they mean by that. Maybe a new avatar will appear in a mission line, like Phoenix did>_> I hope its summonable when it does show up^_-
I don't think they've said anything since the last time they tried to give us good information and then didn't manage to deliver. I'm of course talking about the 2006/2007 promised new avatars with "less perpetuation cost so you can keep them out longer". And while it is true that Alex and Odin have zero perp cost... I'm not sure the "keep them out longer" part was very true when they appeared.

After that mishap I doubt SE will ever tell us about new avatars until the update with them happen. It isn't fun for them or us when things don't go our way.