Overwatch will get a new escort map, Havana, once the Storm Rising Archives event concludes. It is currently being used for the PvE co-op mission to catch Maximilien but will be a fully fledged PvP map, with payload and the whole shebang.
Blizzard have a tendency to introduce new maps during Archives events. Retribution's Venice map became a playable PvP map after the event ended and it was simply dubbed Rialto, after the central part of the city.
Havana will receive the same treatment, except the map will retain the full name as opposed to being named after a part of the city. This is probably because there are two major Overwatch landmarks within it - the Don Rumbotico distillery and the Havana Sea Fort, or perhaps the depiction in the game didn't have enough references to a real-life part of the city to name it after.
Whatever the case, players initially believed Havana would be an assault map, possibly with capture points in the distillery and the fort but this turned out to be incorrect. It will be an escort map and players will have to deliver the payload, presumably from the same point Storm Rising mission kicks off, all the way to Havana Sea Fort.
So far it looks like Havana will be long-range DPS' wet dream as Widowmaker and Ashe will have clear lines of sight to pick enemies off from distance. The initial streets are slightly tighter, but once the payload passes Don Rumbotico, the map becomes widely open with many places where a sniper could assume the high ground.
While Bastion's range is not as long as that of the aforementioned heroes, the Pirate Ship composition should still work wonders since there isn't much clutter to protect enemies from the robot's hail of bullets.
When approaching the fort from Don Rumbotico, there are a few opportunities for environmental kills although it can't compare to the likes of Ilios' Well or Rialto's bridges.
Blizzard didn't state explicitly when the Havana map would be released but it is already on PTR for testing.