One major problem for these kind of cells which are derived from cancer cells is that, even though we can learn from them what could potentially be factors leading to ‘immortality’. We still will need o be able to make these cells grow in ‘normal’ controlled fashion.
We know that once these cancer cells break the rules of ‘mortality’, they also break other rules to follow normal behavior. They act like uncontrolled monsters. Eating up so much resources that other cells start dying.