From Dvoretsky's Endgame manual:
"The theory of the endgame is constantly evolving, although not, of course, as fast as opening theory. New instructive endgames are constantly being played and then analyzed, commentaries on endgames played earlier are being corrected, in large measure thanks to rapidly improving computer programs."
Mark Dvoretsky
Openings which were considered passive or boring have been shown to have merit, or moves in established openings have been shown to not be as strong or weak as thought.
I imagine this will continue for some time...
Are there new concepts and ideas being sprung up still? Is chess truly an infinite game? Is the game still changing?