Dragon Ball Z fans who hated the Toriyama-less Dragon Ball GT, as wel as the awkward-looking Super Saiyan 4 it introduced, will be glad to know that the April issue of V-Jump hints that the upcoming Dragon Ball Z Battle of Gods movie, which Toriyama himself is involved in, will introduce a new stage of Super Saiyan transformation that comes after Super Saiyan 3 (which means the Super Saiyan 4 stage gets retconned, yay!).
According to V-Jump, 39 years before the start of the movie, the Oracle Fish told the antagonist Bills (God of Destruction, dudes.) that there is still a power beyond Super Saiyan 3, which the prophetic fish referred to as a Sūpā Saiya-jin Goddo (Super Saiyan God!), considered as the legendary form of the universe’s most powerful warriors.
Frankly, the power levels and transformations in Dragon Ball have gone way out of hand after Freeza was defeated in Namek, and the issue of what’s canon outside of the manga is equally confusing – as movies are not considered canon while GT had no input from the creator. We’re mostly just curious what the Super Saiyan God would look like.