In my opinion, which is not the most informed scientific opinion in the world (I am by no means a theoretical physicist or even an engineer, nor do I fancy myself as such), disease and suffering will never be wiped out by mankind (by God, one day, but not until the end of times). This is because single-celled organisms are CONSTANTLY evolving. They take on new forms that are immune to medications existing when they do so, and consequently, take new research to fight. Then there are things like AIDS and Ebola which haven't always, if I'm not mistaken, been around. Plus all of the potential for a man-made virus (which is why I really think that it is dangerous for governments to play around with weaponizing single-celled organisms, and what not), either by a government, or by a terrorist group. Not to mention the fact that it will be nearly impossible (scientifically speaking) to prevent accidental death - something that is probably (I can't really speak from personal experience, having only known a few people who have died, and none of them unexpectedly, really) a lot more emotionally troubling than death from a long-term disease or old age. Then of course there are the intentional deaths (i.e. suicide and murder). These things cause suffering. That is just suffering from death (and in the case of some diseases, long-term pain). It doesn't even take into account all of the ways we can damage each other emotionally, even through something as simple and easy as cruel words.
As for the genetic code being altered to extend life, I guess my opinion would depend on what is meant by "altered." I know that scientists are close to (or appear to a layman to be) solving Progeria (sp?) and once they do that, I imagine it is only a matter of time before such medications can be applied to normal persons to slow down the ageing process.
As to the larger topic of Transhumanism, I would say it is - or at least can be - demonic. My reason for thinking such is that it stems from fear, a fear of death. This is not the normal type of fear of death, that almost everyone has, which stems from not knowing exactly what is to await you on the other side. Rather, this type of fear of death stems from a fear of total annihilation because the majority of Transhumanists are atheists or agnostics. Atheists and agnostics do not believe that there is a God (real agnostics only accept the possibility of God). When you don't believe that there is a God, and you don't believe in the soul - which inevitably comes from atheism and agnosticism - you cannot believe in existence after physical death because life becomes nothing but chemical processes, there is nothing more to it. Transhumanists make absurd claims (such as completely integrating humanity and computers by the middle of the century) because they are frightened and want to believe that they will continue to be, 300 years after their birth. They don't want to face the possibility that they can cease to be. What makes Transhumanism demonic is that it takes people away from thinking about life and the after-life by focusing on a search within themselves and a search for God, and twists that fear of ceasing to exist and of death into a technological search for the next big thing that can keep them going in their present life. It is a demonic delusion that leads people away from God.