Spotted over at SSC, from a post by Sr. Horn. It will be called the 235 series. Introduction in autumn of 2015.
The trains will use either hybrid or full silicon carbide inverters, replacing the silicon inverters used on previous designs. Instead of TIMS, a new system developed by JR East, called INTEROS, will be installed, offering 10x faster transmission speed.
http://www.jreast.co.jp/press/2014/20140701.pdf