While a new hero, Orisa, was recently announced, the test servers for Overwatch seem to suggest that the first character unveiled after the release of the game, namely Ana, will soon be nerfed.
In fact, she might experience a drop in the damage inflicted by her Biotic Rifle, from 80 to 60, as well as a decrease in the care and damage of the Biotic Grenade. The damage would go from 60 currently to 30 (on the PTR server), and care from 100 to 50. But that's not all, she is not the only hero to undergo modifications on the Blizzard test server as Sombra, Zenyatta and Winston would be in turn buffed.
Although these changes are not final, given that they are still in testing, although they might significantly change the course of the fights to come.