Its hard to compare hip hops ascendance to dance's potential. Hip hop stations were largely of two varieties- urban stations that shifted from playing R&B and some pop/rock in the early 90s or new Rhythmic stations that were born out of wanting to attract a young audience that liked hip hop without wanting to call yourself an urban station and be seen as only serving Black listeners. To boot, this happened in the era of diaries and not PPM.
Dance stations would have had a much easier go of it under the old system. You are correct, though, that dance has the potential to do what hip hop did and crossover to the mainstream. I think its still a little early to see if its a fad this time around (again) or if its truly entered the mainstream. Only time will tell, unfortunately. If you view the recent EDM emergence as akin to the rise of hip hop in the 80s, though, than I wouldn't expect for there to be many dance stations yet, outside of non-commercial stations like college stations, pirates, etc.
Hip hop started out as a lifestyle for young, urban youths disenfranchised with society and grew into a mainstream element. I don't know that dance is there yet, or if it will ever get there, but it looks more promising this time around than in any time in the past. I'd say the emergence of sell out shows by EDM acts at venues like MSG and Staples Center, the growth of Vegas as a place for DJs to have permanent residency, and the acceptance of EDM artists like never before at music festivals like Coachella point to this movement having a more long term chance at acceptance.
