I am sure that Liverpool will be fine, I cannot say if they are going to end up being in the title race again or not, but last season they were leading the league until a very last moment, then they lost points back to back after that Atalanta loss, I guess their morale just got destroyed after that, and they finished third because of the points lost on that period.
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I don't expect things to be easy for the Liverpool this season.
Changing the manager always brings some disruption and uncertainty. New managers (especially the high-profile ones) do not tend to copy their predecessor's style and vision, but ar rather interested in imposing their own style.
Klopp was one of the best managers the Liverpool has ever had and will be hard to replace, but even with him, things were not always so rosy.
Arne Slot is not very experienced and has never coached outside of the Netherlands, and the Premier League is incomparably harder.
You are not alone on this, I also do not think that Liverpool will complete for this season's English Premier League title. They have been in competition for this title for some time now and in the just concluded season they were major contender for the title but it was unfortunate that they meet at in the 11th hour with Arsenal. That was just a complete team with an experienced coach with a long track history of success in the club. But now that some of the team members of the club will be should missing and a new coach in place with new ideology and relationship. I think they will not be contenders this season. However, they will still make top 4.