I have niche interests to go with a somewhat niche career. My DH has more regular tastes than me sports (something I am not interested in much although I enjoy his enjoyment of them) mostly but we have plenty we enjoy together, we go to the gym together, cook together, watch movies, travel, board games, some theatre, comedy gigs, meals out. We get on great and are very compatible.
When we first dated my DH sometimes worried that he didn't share some of my more obscure interests and that I might find him lacking in some way. None of this is true at all. I've met loads of guys through work or hobbies and while it might be interesting to converse with them about a particular topic or area of interest having a shared interest isn't especially a basis for a relationship or attraction. As an immature teen I probably did think similar interests equalled compatibility but its not the case at all.
Pretty much none of the boyfriends I had based on a shared interest turned out to be compatible and often they were the antithesis of what I wanted in a partner. In my experience actual compatibility is based on something much more fundamental than liking the same stuff such as your values, your goals and the kind of life you are both working towards, communication style and so on. I think as long as you have enough similar interests to spend quality time together then having your own separate interests is quite nice and gives each the opportunity to share them with the other on occasion or just do your own thing alone or with friends.
Do you think sharing a majority of interests is important or is it more important to be compatible in other, perhaps more fundamental ways?