I feel sorry for him. Depression and anxiety do seem to be common among writers and similar creative types. I’ve run into quite a range of artists one way or another, and it does seem to lurk in the background for so many people. There but for the grace of God, etc. I don’t know Douglas Hulick’s work, but I hope that he writes again.
It must be extremely difficult to produce work when dealing with real, large-scale pressure (of course, it would depend a lot on the writer). I have been asked by about six people when I will be doing a new Space Captain Smith book (it’s in progress) and yes, I feel considerable pressure and worry that it’s not as good as the last one. And that’s comparatively nothing. Goodness knows how George Martin must feel. The prevalence of social media can’t help. I get the feeling that, before the internet, SF writers just fired off a book every so often to explore an idea as they wanted, and that was that. Now their progress can be followed closely, and people can demand that they get the same as before, except better and different, and then trash the book on Amazon.
Given that many people are attracted to very long and complex serials, especially in fantasy, I wonder – very vaguely – if we will eventually see more stories being finished by different people to those who started them, if the starting author dies or is too unwell to finish the story. But that's rather off-topic.