A funny thing happened to me on the way to this post. I realized over the last century or so science delivered exactly that. We can debate whether it was only one century or closer to two centuries but that is what was delivered if you count it by average life expectancy. What we saw was almost all eliminating most infant mortality which all by itself nearly doubled the average life expectancy. In fact most of the differences in average life expectancy by country are based upon reporting infant mortality.

Back in the 1970s Sweden had an average life expectancy some six years greater than the US. The US counted infant mortality by the rule that a single breath meant alive and failure to take a second breath was a recorded death. Sweden required survival for six days before a child was considered alive and a death reported only on the 7th day or later.  Careful of statistics, always!

So in fact we have all "accepted" a doubled lifespan on average. And we have designed a society around it. In the US social security was based upon an average lifespan of 67.7 years so all the payments for an age 65 retirment made sense. Before you react look at the previous paragraph about how average is calculated.

In practice in the US (and likely true of all western Europe) we have extended the life of those who live to age 50 by a very significant margin. In the 1950s and prior if a person did not die of a heart attack the doctor would tell him to go home and put his affairs in order as the next heart attack was due in 3-5 days and it would be fatal. Today we get a pill and it the second one rarely happens and it is rarely fatal.

A half a century ago in the 1950s the same was true of a stroke. Back than, What is a ventilator? that thing we debate taking away from those in a vegetative state and theists.

Back then who cared about cancer? Most people did not live long enough to get it. Altzheimer's? If I quit smoking I might live long enough to get that disease.

So far our problem in extending life expectancy has been encountering new diseases because of it. Cancer changed from a random disease slightly dispositioned by age to one that is greatly dispositioned by age once people started living long enough.

So tell me, what is the difference between accepting immortality and taking an aspirin a day to prevent heart attacks? It is only a  matter of how much life is prolonged.

Now if you are imagining immortality is presented in a simple package now instead of modest extensions of life over time you are talking about a miracle which does not exist in this reality.