That's an interesting premise, and transfusions from young donors might be an option, but drinking blood? I would think the digestive process might negate some of the advantages.
It is possible that Kim Jung-Il may have tried injections, but since he was only 70 when he died, I'd have to question how effective the injections were. Wheter or not they discover the answer/cure in blood (possibly in the stem cells), I'm sure the answer is in our genetic code. Given enough time, scientists will most likely uncover many of the secrets hidden in the human genome.