Larry Niven wrote a series of books examining potential consequences of longevity and immortality. I think World Out of Time was quite an excellent exploration into the consequences of immortality for the human race. If man lived beyond his allotted time, humanity will eventually organize their society into a highly centralized totalitarian polity, with social rigidity that would make the Hindu caste system progressive in comparison.
Immortality, and even longevity, would be limited to the elite ruling class. Such possibility would need to be kept in extreme secret, lest the hoi polloi rebel against their rulers in order to access the elixir of life. After all, what would not man risk for immortality? Unless humanity is organized under an absolute totalitarian oligarchy, civil society will collapse and anarchy inflicted upon humanity. Even if all of humanity is granted immortality, the problems of "equitable" resource distribution remains; in fact, it would be of greater problem, since potentially, the social classes will become rigid for all eternity.
I don't really know what would happen, but I often argue for the exact reverse of what you said: immortality is the only way to guarantee equality. You can't rule over 1000-year-old citizens. They'd be too wise. They'd have to go out of their way to remain ignorant for so many years.
No technology, I think, has ever been successfully banned. The uber-rich will discover immortality, if we don't. They're drinking young people's blood as we speak, like some sort of literal vampire. They suck people dry financially and they'll do it literally if they can. Public science must discover immortality or else it will be discovered behind closed doors by private interests. And then good luck opposing them: how are you gonna fight an immortal tyrant, who presumably will have the brains to match his increased allotted time? (There's always the possibility that the elite would be a beneficent one, of course.)
I'm promptly adding the book to my wish list!
I think our different visions of the future has basis on our assumptions regarding the human tendencies. I think more along the line of Farscape writers who envision an imperfect universe populated by inherently selfish, flawed, unwise sentients. Some view the future along the line of Star Trek: TNG writers who envision a cure for human foibles via technical and material advancements.
The blood infusion scheme is an interesting phenomenon, as almost all human sociocultures have myths regarding vampyrism. It may be there is some truth to the claims of the wealthy engaging in literal vampyrism; the magazine article may be a propaganda piece to normalize such behaviors as mere ecentric fansy of the elite.
Another aspect of human immortality would be scientific progression slowing to a crawl. Would there be any incentive for new discovery, when timescale is measured in eons? Why risk disturbing the status quo, when eternity lies ahead? Would men voluntarily live in cryogenic/hermatically sealed cocoons, interacting only via virtual simulation, lest they risk physical death through accidents? If you had eternity ahead, would you risk a premateur end by daring to step outside of your home at 24-30% probability of death?
Many good points here.
Regarding the crawling of scientific progress, it depends on what kind of cure you're envisioning. The most realistic right now is the kind of cure where we constantly need to be one step ahead of Death. Every individual "cure" will grant us maybe 20-30 more years, and by the time those are up, we'll have to figure out a way to beat the new issue that will inevitably come up. Doubtless this will some day cease to be the case, though.
Which leads us to people locked inside shells, interacting only via VR. I think that's a very plausible concern. The greater our potential lifespan, the more valuable our life becomes, which means death becomes a far worse thing. If I die now, I will lose a mere let's say 50 years of potential future life, and a 30 or so years of past life. If I die in the future after 'immortality' has been invented, my death might mean thousands of future years lost, and thousands of past years of investment as well. So yes, people will press governments (or the equivalent) to up safety measures/features greatly (driverless cars would be a simple example), and ultimately they'll stop going out of their house at all.
But there's so much we don't know. Maybe we will merge with machines, and we'll have many backups of ourselves, so if any individual token of the type 'John' perishes, it's no biggie.
Generally, I look at it more in terms of inevitability: I think it will happen, so we should better prepare for it. With the birth rates now, we're facing an economic apocalypse in the future. It's well-known and uncontroversial among economists that the population needs to keep growing to sustain the old. It's one of the reasons countries like Germany, with their birthrate of 1.5 per 2 people, are so eager to let immigrants in. But this is an unsustainable system, climate- and planet-wise. So the way I see it, unless we become immortal, we're doomed. Space travel is science fiction at this point, whereas mice are already living 5 times longer in labs. If it were cancer they'd already be in human trials.