It seems that scientists are nearing an anti-aging drug.

Suppose that the scientists succeed. (I am not a biologist and don’t know all hardships on the way, but biologists seems to say that they are near this target.)

We, Christians, should take “the pill” and live 900 years like Methuselah?

Yes, we should:

(Deuteronomy 30:19) “… I have set before you life and death, the blessing and the curse. Therefore choose life, that you may live, you and your descendants”.

It clearly tells us that we should choose life not death.