how do dancers look to universities.

I think it'd be noted as dedication rather than lack of diversity because mot university applicants say have 2-3 extracurricular on their profile whether it be short or long period. I don't think it'll hurt by sticking to one because at least one will help you when applying to college plus your amount of hours into it is great. For example say you only did one sport all throughout your high school years that'd be fine even when compared to a student that does multiple like maybe clubs and multiple sports. Sometimes colleges don't look for a perfect candidate or over achiever if that makes sense.

I believe that it depends on what college you are thinking about applying for. Some may see it as a lack of diversity simply because you invest all of your time into it. On the other hand, some colleges may see a substantial amount of dedication to dancing and will view it as an attribute rather than a lack of diversity.

I think schools would see it as dedication. I've heard that collages want a well rounded class, not necessarily well rounded students. So if you show consistency and dedication to dance, that would most likely be a plus for your application.