Blizzard has announced that Overwatch: Classic will bring many of the original elements of the original game back in a series of events.
The first event will take place on November 12th until December 2nd taking it all the way back to the original 1.0 release from May 2016, including many abilities that haven’t been seen in years.
This will bring the original 12 Overwatch maps back to modes such as Assault, Escort, Hybrid and Control. The full update that can be read on the Blizzard website says that the heroes will be grouped in their original four classes but you will not be required to only play as attackers when on attack or defendeers when defending, instead being able to pick the best hero that works for you.
For the first few days there will be no limits on picking heroes, so there will be able to be the same six heroes on the one team, but this will be turned off a little bit into the event.
Overwatch: Classic will appear as a mode within Overwatch 2, and I highly recommend checking out the the FAQ on the Blizzard website for more information.