It’s was a strong rumor for the last two years but its been confirmed that we will get a whole new redesign on super saiyan level 4 and its been named Super Saiyan God which Goku reaches to defeat Bills.
It was confirmed by a Japanese magazine and the latest Dragon ball Battle of Gods trailer.
The transformation works in a similar was to level 4 where Goku turns into Oozaru then controls the beast to gain its power.