All Marvel fans would know this famous quote from Endgame:
“In order to take the stone, you must lose that which you love. A soul for a soul…”
This is the mandate that had been set by Red Skull during Infinity War when he had told Thanos that he has to sacrifice someone he loves to get the Soul Stone and its powers. He then threw Gamora off the cliff. Avengers: Endgame then opens up the Quantum Realm, and one again facilitates time travel and all the mind-melting possibilities.
In the realm of the Avengers, Joe Russo had clarified that the Soul Stone sacrifice is irreversible, and this means that Black Widow and Gamora are gone for good.
They might be ‘gone forever’, but they are not necessarily gone forever. Scarlett Johansson has agreed to star and also produce a Black Widow prequel film, which will be set in and around the timeframe as the film, Captain Marvel. Gamora will be seen in Guardians of the Galaxy Vol. 3 as well, and it may be that James Gunn is cooking up a huge plot that will see our space-faring A-holes trying to rescue the Gamora of 2014, who had been dragged into Endgame‘s timeline.
It is pretty confusing, but it does leave the door open for Gamora’s return and just in time to see the Asgardians of the Galaxy.