What do you mean he will continue to struggle? Did you get the impression that the coach or the players struggled in the Champions League quarterfinals? It was quite the opposite. Yet, the only right decision is to get rid of Tuchel. Surprisingly the guy always finds another big club to immediately get going after he gets fired. Once these coaches made it to the top of the list in the world, it doesn't matter what their results are. They sign contract after contract. Just look at Pochettino, one of the worst in the business. But he doesn't care, next club will be waiting for him when Chelsea fires him.
Thomas Thucel is not a coach who is really suitable for Bayern Munich, the proof is that he failed to defend the domestic league title in his first season with Bayern Munich, not because Leverkusen performed well. It's just that Bayern Munich failed to maintain its consistency and continued to pressure Leverkusen every time Bayern Munich had a chance to overtake Leverkusen, Bayern Munich always wastes these opportunities so Leverkusen continues to be in first place without ever being overtaken by Bayern Munich until nearing the end of this season and has widened the gap quite far, even though in the Champions League Bayern Munich still has a chance to win the title but its opponent in the semifinals is Real Madrid. So I'm not sure Thucel is able to provide a good enough strategy, Carlo Ancelotti's strategy is more effective than him.
So yes, it would be better for Bayern Munich to fire Thomas Tuchel who cannot provide a better strategy than Nagelsmann, firing Nagelsmann can be a valuable lesson for Bayern Munich not to be reckless in firing a coach like Nagelsmann. In the end, Bayern Munich actually got bad results this season, hopefully next season Bayern Munich got a really good coach to replace Thomas Tuchel.