Isn't this covered in multiple sci-fi genres? There's no real way to distinguish immortality from what amounts to a pre-planned death around some kind of life extension procedure. As a social group, we're more likely to select something that is effectively "continuation of thought patterns" than we are to actually extend consciousness

I think brain and eyes within a vat are completely within the realm of possibility in the very near future if not already. That would definitely register to me as extending consciousness with no preplanned death.