The Vacuum Tubes Last Stand!

I think the better title would be "Arrested Development."  There has not been much in the way of developing new tubes, much less tube types, in recent times.  

Vacuum tubes still used in aerospace ? I didn't know that.

I think, tubes will continue to be present for the foreseeable future, and overall more people are getting interested in vintage technologies - vacuum tubes, tape decks, turntables, books, handmade things.