Update 06/26/18: The Overwatch account has now posted a second teaser set in the same location as the first – the difference being that a gigantic, rolling… something now rolls through the shot.
Many are speculating that this is Hero 28, although some have speculated that it could be to do with the return of the annual Summer Games event. That event usually kicks off in August, but it could perhaps come a little early to tie into the FIFA World Cup taking place at the moment.
Rolling through. pic.twitter.com/T3fPXbTMQl
Source: IGN.com Update: Overwatch Posts a Second Teaser, Possibly for Hero 28