Again, The Census Bureau is hardly an authority on this matter - they're concerned with the challenge of just logistically counting Americans every few years via surveys (the lowest order of the scientific method) and it's questionable how precisely they even do that considering I can attest to having missed one such survey myself years ago. I treat their predictions on longevity with the same skepticism I view their census stats, which is optimistic given the massive gap in expertise. This, by the way, is in no way an attempt to diminish the very real and difficult challenges this task presents - only to place their expertise accurately.
Experts very much DO NOT agree on this and the fact that literally billions of dollars in R&D are expended on this area of science in just the US is testament to that. Sure it doesn't mean any groundbreaking discovery is guaranteed to happen - but it does show that belief in the possibility is alive and well. And why not? Those immortal jellyfish share 97% of the same DNA, including long stretches of matching sequences and compatible genes that have been experimentally transferred between them and other life forms numerous times. Even Right Whales, which are conscious mammals sharing immense biological relation to people can live 200 years or more, and that's in the absence of anything remotely resembling science and the presence of numerous impediments, including us, their generic brethren. Tardigrades may end up being miniature space suits for the most advanced intergalactic life forms known - who knows? What we do know is they throw most of what we believed to be true about life and morality right out the window - and that's a good thing. All this is to say that the possibility of longetivity increases driven by scientific exploration is much greater than the likelihood of that not being the case.
Kurzweil is who he is, for better or worse. But he has made outlandish predictions over the years, many of which have come about despite the skepticism. He's a successful entrepreneur and employed in a very senior position at one of the most valuable and forward looking companies in the world. He's not everyone's cup of tea, but I don't completely dismiss him as a crank. I disagree with some of the time lines he has, though cautiously because it doesn't take many compounding discoveries to get there on his schedule. But fundamentally, I agree with much of what he says - even though I think what they mean for us as humans and the universe as a whole is much less certain, and likely as scary as they are promising.
EDIT: here are some links you might want to read to confirm that whole "experts agree" conclusion:
Henrietta Lacks - the woman whose specific cancer mutation provided the vast majority of cells used to study cancer and numerous other cellular process, to this day. Cells which are effectively immortal: http://www.todayifoundout.com/index.php/2010/05/there-was-on...
Immortal Jellyfish, from that disreputable rag, The New York Times..:
http://www.nytimes.com/2012/12/02/magazine/can-a-jellyfish-u...
Just search HN for immortal and see what you find, then let me know if your assessment remains the same