That's the expectation that all the management and the fans have. All the new coaches can't guarantee he'll be good. We can only see how history he has made. So I think whoever Bayern Munich coach has the same expectations, there will definitely be pressure for a new coach. If it fails then actually Munich have set an example for Tuchel, they can immediately change another new coach. As a new coach I don't see him badly. He has a wide and long range, he can lift Barcelona to the better and I think people have understood.
Don't be a hurry to place offers for Xabi Alonso because alot of things will go wrong, he has not proven to be promising. Bayer Leverkusen is the best club inform in the Bundesliga season. They're unbeaten and ranking first on the table, they're bringing the title home this season. Bayern Munich management targets to bring Xabi Alonso to the club but I don't think it's a wise decision because this is the only prominent season for Xabi Alonso to shine, after this one, check him out next season and watch how everything will play out.
What you say is also true, because this season Xabi Alonso could be very lucky so he can show something truly extraordinary. However, considering his journey since joining Leverkusen, we have actually been shown how Xabi Alons succeeded in making Leverkusen improve in the previous 2 seasons and he was even able to bring Leverkusen, which was at the bottom of the standings at that time, to be in the European League zone at the end of the season. Maybe that is one of my considerations in saying that Xabi Alonso's abilities are indeed very good.
However, I also agree that you shouldn't be hasty in judging something because it might be a wrong judgment. Moreover, Xabi Alonso himself has not said anything about his possible decision whether to stay at Leverkusen or leave. What is clear now is that he is trying to focus first with Leverkusen to realize their target which is currently in front of their eyes, in just a few more matches they can lock up the title as long as they can consistently win in every match they play.