Egan’s writing has two very strong characteristics, but one of them, the ultra hard SFnal aspect, gets mentioned more often than the other. Egan is, like James White before him, one of the few science fiction writers who creates optimistic futures. This idealistic notion that human or intelligent and consciousness life can better itself, not just technologically but also morally, is an equally strong part of his fiction as his hard sf notions.
Often connected to the concept of paradise or utopian societies is the meme that these civilizations will die out, because people who have achieved peace and material comfort, who have left behind wars, diseases and other threats of our age, will inevitably decline because of a lack of challenge. What’s left is the search for knowledge, but what if even that is finite? The story doesn’t give a clear answer, no real solution. What it gives is hope, hope that even when the external source of knowledge seems to have dried up, when it looks like science has ended, the internal variety of the Amalgam, the diversity of an galactic civilization with countless sentient races, will be enough to carry through until the moment when new directions for the search for knowledge have opened.
If you want an interesting counterpoint to this story, read Peter Watts story Ambassador, which is IMHO thematically related, even if it goes at the whole theme from a completely different direction and takes a completely different position. But then, Peter Watts stories are rarely outbursts of happiness.