Ahamkara still exist. If you go to Venus, they can be seen flying around in the sky, as already mentioned. There is also an Ahamkara skeleton on the moon (also already mentioned) that gives credence to their appearance. They are also a very prevalent part of the story. First, they are most likely the servants of Darkness that gave the Hive their power. This is evidenced by their description in the Grimoire and the way that it tempts Auryx and her sisters. Also, the Ahamkara are thought to be the whispers that led Dregden Got into the Darkness. He is thought to have been Pahanin, based on the fact that he was always talking to himself (like how the Ahamkara gear items are supposed talk to you) and some other evidence from the Grimoire. All in all, they're bound to be an important future part of the game.