This really would be a fitting end - losing 0 and 0 in qualies.
No, he never lived up tp the hype (which was overdone like it is for so many players), but he had his okay journeyman career - a couple slam 4th rounds, wins over Murray and Wawrinka, a Top 40 ranking, $4.5 million in prize money, got to play on the biggest stages. My only regret for him is that he didn't win a singles tournament, only made the finals.
My "standard" for journeymen players is whether they can get into the Top 105-ish and stay there at least for a little bit - so that they can get auto entry into slams for a year or two and get that Slam money and points. DY did that on multiple occasions. I don't think he can get there again, or even come close.
Since he hasn't been around in any sort of legit way on the main tour for a while now, I wonder how serious he is about tennis. I mean, if he wants to have some end-of-career fun playing challengers, futures, qualies, so be it. But, at some point he needs to decide what to do next. While I don't think his hands were as special as some people once said, nevertheless he did have decent hands at net, and an okay lefty serve. I'm surprised he never gave it a serious go in doubles. He did make a Slam final, but he didn't seem to consistently pursue doubles, try to try a permanent partner.