I enjoyed the Stephen's thoughts of evolution expanded through external transmission. I don't actually agree because natural selection gets really fuzzy with this model, but it's very engaging viewpoint.

It's also interesting that the whole article is about Fermi Paradox and Great Filter, but he never mentions those two concepts by name. I wonder why?

It's indeed very interesting to imagine how a mechanical lifeform, that would have replaced DNA based life, be like..

I personally believe that as nanotechnology will advance in the later part of the century, biotechnology will be revolutionized and we, as humans, will eventually head towards becoming an immortal society. I'm not sure how long it will take but the developments in nanotech could also lead to teleportation (signs of which are theoretically quite evident among Higgs Bosons).. I wonder if Stephen considers that those phenomena could ever scale up.

The great filter is my favorite hypothesis for the Fermi Paradox too. But as much as I would like to think we might be the first civilization ever to cross the higher levels, I also hope that we don't destroy ourselves with our fast evolving technology.