What do you think about symbiotically or biologically eternal life?

I think that reaching eternity would not be possible. Since generation and decay is the basis of Nature (or metabolism), eternity would simply be unnatural since the metabolism would become non-existent. The good part of your idea, is that technological advancement seems something natural, since evolution brought us to it. It may bring us to advanced aging but synthetic feeding of the body would somewhat become unnatural, and human would become a machine, by loosing his grip with his nature of being a creature seeking sensual pleasure and thrill.