Here are some rumors collected from 2ch regarding the New Rider:
-Name is "Kamen Rider Succeed"
-Helmet had a crown design, the crown is "cracked", coloring red and silver
Name seems to come from the act of "succeeding to the throne."
Please take rumors with a grain of salt, more info is to come, I'm sure. As per usual, the new rider is set to make his debut in the August film.