Living systems - hell, complex systems - don't do "forever" real well. You end up adding a compounding amount of energy over time, a "negentropic tax", as the universe tries to untie that complexity into radiation.
After a while the compounding energy input of the negentropic tax overwhelms the control mechanisms that feed it into the "preserved" system, and it blows up.
It's a common feature across disciplines: content management, biology, programming, maintainability engineering, neural networks, chemical engineering . . I imagine the list is pretty close to boundless. Ha, turns out human knowledge is also a complex natural system.
So I guess what I'm saying is only dead things live forever. Which should say a lot about the internal life of the standard tech/finbro. "I want to be just like I am right this second for all time!"
Speaking personally, I'm always amused by the Eternal Life pitch whether I hear it in church or on the internet. Everyone gets eternal life. We're surrounded by it, we eat it, we poop it out every day. Our grandfathers are in our lungs, old friends in the leaves of trees, giant parts of your brain die every morning as you wake. Eternal Life is not for the selfish. Something that the Bible thumpers could read for themselves, if they bothered to read the thing.