I’m guessing they will all play but different games, let’s say.. Garcia would play mainly Laliga and Szczesny maybe Champions league or swapped to Laliga depending on Garcia performance. Now there’s Stegen who doesn’t want to leave, he would likely play CopadelRey and Supercopa along with inaki Peña or both used as substitutes. Nevertheless, Flick might have a different strategy to consider regarding the goal keepers but for him to have gotten Garcia means he might not be needing Stegen and Peña in the first place yet I hope whatever he’s thinking better be a good one..
This is difficult to implement because goalkeepers with more playing time typically have a stronger mentality and confidence, so Hansi Flick can't afford to do this, as it would pose significant risks.
Having three high-quality goalkeepers is certainly difficult, but Flick can still rotate and compete among them for starting spots. This is also likely a measure taken to prevent injuries and allow other quality goalkeepers to cover for them.
Since Ter Stegen has no plans of leaving and Szczesny is still hoping on fighting for a spot, i think they're still the first and second choice but on the arrival of Garcia either of the have to be dropped for the new goal keeper to be giving playing time cause there's no way Hansi Flick would buy Garcia just to keep him on the bench, those other two have had their moments maybe this is Garcia's time.
Well one thing am sure of is that regardless of who's the first choice for the new season their would be rotation among them but one of them would be on the bench mostly as third choice and I guess it would be Szczesny since he's the oldest amongst all.