Will humans ever develop a longer lifespan?
With medical technology always improving, and our knowledge of health in general always increasing, it is statistically likely that our lifespans will continue to increase - as they have been, gradually, for centuries. Since no one has yet lived to be 150 years old (on record), this age might be a, at least current, threshold which our limited technology and knowledge of human physiology will not allow us to surpass. However, there are many scientists who think this will eventually be surpassed, some guided by the common sense view that over the last 200 hundred years, many people are living longer.
Other, more radical, scientists such as Ray Kurzweil are optimistic that technology will advance so rapidly that living to be 1,000 or perhaps even living forever is inevitable or even sooner to emerge than we think.