The internet has been littered with reports stemming from 4chan leaks about Overwatch's 1st year anniversary event. A multitude of these reports suggest that Doomfist will finally be released with the anniversary event alongside many new skins, sprays, voice lines, highlight intros and maps.
Apparently, there will be 3 new maps; an escort map, an elimination map (3v3 and 1v1) and a map for a brand new gamemode, where both teams compete to push a neutral payload into the enemies' side of the map.
Doomfist is supposedly a highly offensive character, who borrows from Tracer and Reinhardt with dashes that can pin enemies and an ultimate, where he divebombs to the ground causing area of effect damage and eliminating whoever he lands on (think Drogoz's ultimate in Paladins).