Just a phase or will it last?  

It is true. If you have seen the movies and dances of 1930, I thought it is vintage. When 60's and 70's become older now, with your aging, the present one become older even more faster, because the fresh water will flow and it is new and innovative (again this is for 10 years or so). Again new one will come. That is how the life is.

Breakdancing was popular in the 80's as well. This was followed by the more "hip-hop" oriented styles such as the movements incorporated into N*Sync's and Britney Spears' performances. I think pop culture does play a significant role in the dance styles today's young people are interested in - if they develop any interest in dance at all. Whatever gets the most air time and is practiced the most by today's pop-culture idols will likely be the trend setter. I don't watch TV, so I can't make an assessment if this increase in the practice of several popular dance forms is due to the TV air time, however, unless it is one of the more classical dance forms such as ballet, jazz, tap, and maybe modern, I am inclined to believe the popularity is probably some type of a fad generated by what Hollywood and like sources feed out... at least to some degree.