It appears that LiftPort, one of the leading pioneers in space elevator technology has pushed back the initial construction date of a space elevator from 2018 to the current date of 2031.
The company goes on to list reasons for the later date over on their official Roadmap plan:
Although LiftPort is involved in the production of carbon nanotubes, we will likely rely on the global development of high strength CNT materials. While we assume the material will be available around the year 2020, earlier availability will not particularly speed up development of the space elevator. […]
The longest tether ever deployed in space was roughly 20km long. Given the history of problems in tether experiments, it would be imprudent and impractical (at best) to go immediately to a 100,000km system. In addition, much can be learned by smaller scale tether design experiments before the final carbon nanotube-based ribbon material is available.
Although this may come to a dissappointment to some space fans, LiftPort seems to be taking the cautionary approach to pursuing this project, as launching a failing elevator prematurely would doom any push for a future one.
Despite the fact that some space elevator supporters may be senior citizens by the time a viable space elevator comes along, they may at least look forward to the possibility of their children and grandchildren living on the moon or other worlds.
Darnell Clayton blogs at Colony Worlds, detailing reasonable ways to colonize our solar system.