Sad, sad day.
He was often asked about what you mentioned, and he always said something along the lines of to him, racing was not just about the driving, but the designing and building of the cars as well. He got pleasure out of the whole aspect of racing, so he never considered the lack of championships as any sort of regret.
As far as I care, if his 1967 Belgium GP win in his own Eagle was the only racing accomplishment he ever had, he would still go down as one of the all time greats.
I met him at Nazareth when he was running his own CART team. He was signing autographs as if he was one of the drivers, not a car owner. That's how much in demand he was from the fans.
And of course, it was his White Paper that ultimately led to the creation of CART (which BTW, many people do not realize that the intent of his White Paper was not to create a revolution and breakaway series, but to get USAC off their butts and do something about the sport beyond Indy; when they didn't acknowledge anything stated in his White Paper, that's when the other car owners took it upon themselves to revolt), which to this day I consider to have been the greatest open wheel race series in the history of the sport.
Let's also not forget, every spraying of champagne from the podium is a homage to Dan.
You will never be forgotten, Dan.