Wow...I didn't even know. Just last week I was reading his endgame articles in Chess Life with interest. Rest In Peace.
Danny Kopec, RIP

I'm pretty sure the mention him in their newest chess center video. But I know not everyone can watch them.

I just saw this today. I remember Bubby and Zadie's subterraniean deli on green street in campustown in champaign, illinois. And Danny Kopec came to U of I for a year or two in the late '70s and played a generous number of games with us locals in the underground deli. We were a scrappy bunch of experts and he just dominated. He took me and another expert on blindfolded while we played with view and he beat us both. Very nice guy, even online. I used to play him on icc and got lucky very seldom. God bless you, Danny.... you were a class act.
Danny passed away and Chess.com hasn't even bothered to make note of it. Shame on you.