If we are talking about Atletico Madrid's chance to win a Champions League title, then I don't think it will happen in the near future. 
While Real Madrid is getting Mbappe and there is a Manchester City fact too, it is really not easy to reach the title. Besides Atletico Madrid's lowest expectation in this tournament isn't winning the title. Even a quarter finals qualification is seen as good achievement.
The board are really contented with the way Simeone is managing the team. They even extended his contract not much time ago. Would he like to achieve a Champions League title? Who wouldn't?
But Atletico Madrid need to make a huge improvement to reach even the finale once again (The last time they did it was the 2015/2016 season).
Atletico Madrid played in the 2014 and 2016 final of the UEFA Champions League competition which was the close to times they almost won the the UEFA Champions League title but unfortunately for them, it was their biggest city rivals Real Madrid that they had to face in those finals of which they were beaten. Currently, I don't think they have the squad that's strong enough to challenge for the title and despite their struggles in recent seasons they've always decided to stick with their manager Diego Simeone. While Real Madrid is getting Mbappe and there is a Manchester City fact too, it is really not easy to reach the title. Besides Atletico Madrid's lowest expectation in this tournament isn't winning the title. Even a quarter finals qualification is seen as good achievement.The board are really contented with the way Simeone is managing the team. They even extended his contract not much time ago. Would he like to achieve a Champions League title? Who wouldn't?
But Atletico Madrid need to make a huge improvement to reach even the finale once again (The last time they did it was the 2015/2016 season).With the club under Diego Simeone, I don't think they are going to be a major contender for the UEFA Champions League competition anytime soon because it's still the same tactical approaches he's adopted in recent years that he'll continue to maintain.
On the issue of ATM losing the champions League finals to Real Madrid in 2014 and 2016, Diego Simeone once said if not for C Ronaldo his team would have won two champions league but that been said, I think football is unpredictable yes ATM have had their best moments yet they were unlucky to win the champions league finals but that doesn't mean their style of play is not good to win the trophy or their coach can't lead them to the finals no I think the current squad in the team can make it to the finals and can win the trophy if they improve in their performance or get lucky to defeat their opponents to get to the finals and end up defeating the team they play against in the finals. Last season Dortmund was in poor form they couldn't finish in the top4 in their league but they managed to get to the final of the champions league despite struggling in the league, they had the opportunity of winning the champions league if they had converted their chances to scoring goals so I think Diego Simeone still has what it takes to take to his team to lifting the champions league trophy sooner than we can imagine even without having to change his playing tactics.