A new variant cover by artist Tony S. Daniel for November's Superman #34 teases a Legacy-style renumbering that would take the comic to triple-digits for its 800th issue.
When DC Comics launched its Rebirth publishing initiative, it continued the majority of its series with the numbering that began with the New 52 in 2011, with the notable exceptions of Action Comics and Detective Comics. Those two titles reverted back to their original numbering of #957 and #934, respectively, in a move Marvel Comics is currently implementing for a number of its long-running titles in Marvel Legacy.
According to a report on Newsarama, Superman is one of several series receiving legacy variants illustrated by Daniel. Arriving in stores this fall, the other variants include a Wonder Woman 700, Batman 800 and The Flash 700 also planned. Whether the series will make the change to reflect this in their actual month to month numbering remains to be seen, though the publisher is reportedly referring to these covers as celebrating the respective character's 700th or 800th "adventures."
The Superman variant depicts the Man of Steel busting out of green Kryptonite chains while standing atop a mound of rubble. The number 800 is formed out of cracked stone and can be seen displayed behind him.
The fourth volume of Superman is being published under the Rebirth banner. Technically speaking, if you add up all the single issues of Superman in volumes one through four, they far exceed 800 issues. However, if you started counting from the final pre-New 52 issue's #714, then the 800 would make sense.