If Bayer's fans are so naive that they expect a Bundesliga title this year, then they needn't worry - if Alonso leaves, it won't be until next summer. Bayern are showing dubious results so far, but still their chances are higher than those of other clubs, take a look at the bookmakers’ quotes:
Bayern Munich 1.24
Bayer Leverkusen 9.50
RB Leipzig 11.00
Borussia Dortmund 12.00
No surprise to see bookies gave that small odds for munchen as this club has been winning this league for more than 1 decade. To be honest, if leverkusen has a very big chance of winning the trophy this season. The sense choice to pick bayern as the winner for this season but taking the risk to pick leverkusen was not that bad. The only possible club to recruit alonso was real madrid. I don't see another team who has been declaring their interest to recruit him.
Madrid already listed him as a potential replacement for ancellotti next season but i was not expecting ancellotti to leave from there in winter. He probably stays till end of this season.
It's pretty interesting to wait the performances from those clubs till the middle of this season.
These are not such small odds - last season they were mostly 1.05-1.06 even when everyone saw that Bayern was slipping a lot and was not what it was before.
9.50 is an excellent odds to take a risk, but not in the case of long-term bets - you can wait 15 years for the risk to pay off. Even if you win similar bets after 5 years, it is unlikely to bring joy.
As for Ancelotti, he will work till summer 100%, there is no reason to change him in the middle of the season, his replacement is just part of the renewal strategy for Real, so this will be done in the normal manner.