I do think that effective biological immortality will be acheived. I don't expect that it will be available to everyone, and I'm not sure that we will be able to appreciate it for long, due to the likely emergence of immortal AIs. I am a biomedical researcher. I expect that most cancers will be cureable within the next 20 years or so, mostly through employing a patient's own immune system against the tumor. This will greatly extend the lives of many people. However, I think that problems like neurovascular disease will be more difficult to solve, and I expect that it will be 40 years or so before therapies that effectively reverse the aging process will be available. I haven't read Kurzweil, although I think that there is a likelihood that non-biological AI will inherit the Earth from us.