I am sure that there are a number of niches that initially have a certain demand and will always be popular. Health and everything connected with it, including sports. Education and development. Leisure and recreation. In any case, it is still difficult to talk about what will be really in great demand.
1. The question of the coronavirus is not closed - it means that medicine will probably be more relevant than usual.
2. Everyone began to spend more time at home; leisure time demands diversity. Games, VR, etc.
3. And of course self-development, various training programs will only develop more actively.
In any case, when choosing a topic, you should focus on yourself in what you are an expert and in what you would like to develop, so you can create a truly interesting blog
This is an extremely subjective opinion. Friends, I ask you to be critical of him.