Interval workout the new prescription for run speed?

Sprint is one of the most famous, efficient and 'easy' to perform Tabata training. In this article, the author is wondering what " type of intervals should we be doing" to increasing our speed on the run.

Mile repeats? 400's? Farleks? Tabata intervals? Yasso 800's?

Check the link: http://www.nola.com/running/index.ssf/2012/06/interval_workout_the_new_presc.html