If this deal went successfully Barcelona will really be happy and will meet their target and they will probably regain their form and they may probably become very competitive and they can make top four this season, because, Adama Traore is very strong and promising player that have the ability to deliver and attack from the wing, I think if Barcelona were able to make the deal successful there will be some smile in Barca fans face.
I do not think that one Traore transfer would change too much with them. I mean yes he is a good player, but the problems with Barcelona is not one player away. Plus, interestingly for a Barcelona youth team player, he is very fast and strong but his technique is not there, he is not a great finisher and he is not a great passer neither, he is decent but not a good one.
So, this transfer will not really change much for them, would make them slightly better of course, who wouldn't want a player like that, but it will not make them suddenly a team that dominates everyone else, he is not a superstar type of player that can change a team all that much just by himself.