Could there be a realistic way where people are given eternal life by maybe "downloading" your conscious somewhere and then after you die you can "reprogram" it into something else which allows you keep living even longer? Given that science and technology has gotten extremely complex, I think that this is possible as well.
the problem with this is the "gap" between you dying and the uploading on the device. I just can't be persuaded that the copy will be me, although maybe that copy will tell everyone he is me.
it can even get more crazy: if you can "reprogram" a device with your consciousness, it is perfectly possible to make multiple copies of "you".
This is certainly not a solution...
edit: immortality is imho impossible because chaos theory. It's like a perpetuum mobile on a universal scale.
Slightly on topic: even the XMR blockchain will not be able to be intact forever:
What is the chance that at least one copy will be preserved forever?
Because there is a non-zero chance that all copies of the blockchain will be destroyed in the future, monero isn't "immortal".
Sad but true.