That trick tends to only work once, and with each successive attempt at threatening to leave the response gets weaker.
Also, without a significant increase in quality and/or quantity of his output, or new content ideas, people who donated to get him out of a hole will start to ask questions.
If he just slumps back to the bare minimum he can be bothered with, if he's slow to post on breaking news, and if he can't get anyone of interest to provide him with new or relevant content, then donors will be asking - what's the point of keeping his channel afloat? Especially if he's snarky and aggressive to anyone who asks questions about his content or offers suggestions.