No one is saying Alien for Marvel rights. The theoretical is "Alien for Black Panther". If i'm Comcast, I force Disney's hand and say if you really want this you'll also give us x, y and z AND you have to agree to make an Incredible Hulk MCU film.Alien rights don't equal Marvel. They would have to give up something else very valuable for that trade.
Obviously it wouldn't be a straight up trade if it were to even happen. But like I said, Black Panther is only a small, small portion of the Marvel contract and think of the return they could get just for him. Comcast would be crazy not to at least think of scenarios and ways to swindle Mickey is all i'm saying.