I don't think it's a one-time thing though. Madrid has been really inconsistent this season and a lot of times they've been bailed by the individual quality in their squad. Madrid has so much quality that any player can produce a moment of magic at any time and that is what happened against Atleti.
Days when the individual quality doesn't impress or when the opponent play better, they suffer.
I don't think Madrid would be able to win the La liga because they will still drop more points in the league. I agree that the other 2 teams will drop points, but not as much as Madrid. The champions league and Copa del Rey are the only hope of Silverware for Madrid this season.
Real can come back, they are a team that will not give up until the last round, but they are really inconsistent this season, and now besides Barcelona there is also Atletico, who can simply not allow them to come back again.
I also doubt that Real will be able to defend the champion's title, Barcelona deserves it more, Flick has made a very good team and they are ready to win, they have proven this more than once, they smashed Real and Bayern, it was something.