The article made a convincing case that with existing and foreseeable technology the space elevator wouldn't work. Convinced me, anyway. And Frank's supposition that by the time it was feasible the need would have been leap-frogged by other technology also makes sense. Convinced me, anyway.
And there are surprises. 50 years ago the availability of massive computing power was a ridiculous pipe dream. So, too, the ability to find and identify DNA. Practical light from cool sources (LEDs) wasn't imagined as far as I know. Superconductivity at warmer temperatures was a surprise.
Some similar breakthrough in the manufacture and bonding of nanotubes might be possible, similar to the ability to duplicate infinitesimal amounts of DNA. A stronger, bigger cable capable of withstanding or avoiding the stresses which are a deal-breaker now could become possible. I doubt it, and we've been surprised before.
(As I sit here typing I remember a reasoned article I read years ago which claimed word processing by computer would never be useful because computing involved numbers, not letters.)