Under no circumstances human beings can ever become immortal in physical form. So was not ordained by God. The human form has an average limited time span of 100 years. Even before that the body starts disintegrating. What do we expect to achieve with an ailing body?
No matter to what level science or medical science progresses, immortality in physical form will never ever become a reality in present or in future.
The reason is apparent. We are primarily a spiritual traveler, a spirit manifesting human body. The human form is but a medium for the spirit within to regain its lost original pure prime pristine primordial form. The whole crux of spirituality is becoming a pure soul atman forever.
Our soul atman, the spirit is the actual master and controller of human body. In the circumstances how could physical body become immortal ever?
The spirit, soul atman existing in our heart was always immortal, could never be created or destroyed and exists from times immemorial. No sooner human beings gained enlightenment and finally moksha salvation the liberated soul atman enters abode of God (Vaikuntha in Hinduism).
The life journey of a spirit, soul atman came to an end when human beings gained enlightenment.
Yes when human beings indulging in spirituality gained enlightenment, they became immortal through their teachings forever. All these man gods Mahavira, Gautama Buddha, Jesus Christ and Prophet Mohammed after reaching state of enlightenment gained immortality in their lifetime. And so did Adi Shankaracharya, Sri Ramakrishna Paramhansa and Maharshi Ramana.
Mankind should never look forward to immortality in physical form as the human form, the body starts giving way after reaching 70 years of age and some even earlier.