Is this developer going to release any other projects?
I don't expect so. At least not for a while. As I understand it, the stress of making and promoting the game was having a negative effect on his mental health. He chose his health over the game.
I expect one of the challenges is that many developers are working alone or with a team of individuals that have joined for the project. Many are not out to those closest to them, the ones who could keep them stable when things get rough. Like Peter Parker, having to live two lives can take a toll. I feel that if more developers could share their passion for making the games with friends and family and those people give their support, we'd have fewer cases of developer burnout.