Atletico Madrid don't want to take risks by replacing Diego Simeone, so they will continue to keep him until Simeone gets bored of being at Atletico Madrid. Indeed, they are stable under Simeone's coaching, I mean they have not experienced a very significant decline that makes them have to drop out of the top 4 for example.
I can understand why Atletico Madrid are too "scared" to fire Simeone, because there is no guarantee that they will be better under the new coach. but the problem is that they will never know whether they will achieve success if they are in the hands of a new coach or not. Maybe they will be more successful with a new coach.
But this is definitely something difficult for them, because they must also consider everything before deciding whether they will keep Simeone or not. What is clear is that we will still see Atletico Madrid with their coach.
Even if they wanted to replace Simeone, can they actually do it? We must remember that Simeone has been for the most part liked by his players, so if those at the top of Atletico Madrid fire him with no justification at all, then the players will get mad about it, they may underperform to get the new coach fired or even ask for their release, so this is not an easy choice to make as I am sure that before any improvement could be seen, a massive drop on the performance of the team will be observed.