It's not yet over until it's over. The season hasn't come to an end that we only have one or two matches to play that will make me accept with you that Barcelona has already won the title. Real Madeid is still open to winning the title because we can't tell if Barcelona will be able to stay on the first position till the end of this season.
Barcelona will slip back down if they lose one and draw one of the remaining games that are still left in this season. That means one loss is still enough for Barcelona to stay at the top and have a chance to become champions in La Liga this season, but as long as there are still quite a lot of games left and the season is not over and there are still points from certain teams that are quite close to Barcelona at this time. Of course we don't have to immediately say that Barcelona will be champions this season because a change in position is still possible if Barcelona doesn't win continuously until the end of this season.
Barcelona are still not comfortable and keep in mind that they and Real Madrid still have the second leg in that game we can see a clearer picture of who will lift the trophy but to get there both teams need to consistently win every game and Atletico also still have a chance because after all the points difference with them is still very small.