The LED was invented in 1962, with research into creating a "solid state" laser produced a visible light. Researchers in 1962 knew that "solid state" lighting was the future, but they had no idea that it would be another 50 years until all the elements of the technology would come to place to make the it a practical lighting solution for the masses.
I was at Walmart last night and I noticed how many LED light bulbs they now have on sale. It seems almost certain that traditional vacuum-tube style lighting (incandescent and fluorescent) has less then 10 years left in it's life -- prices continue to drop -- and LED lighting is now superior in most ways to the vacuum-tubes that have long lit our buildings.
Sometimes innovation takes a long time. Who would have ever thought a half century would pass before we would light our buildings with something other then vacuum tubes? Vacuum tube electronics disappeared within 10 years of the introduction of the transistor and solid state electronics, but it shows you how different technology progresses at.