They are still extremely competitive, but it's always the same with world class players. When they are out for some reason, the team loses some of its world class. It would not be like that if the players weren't world class.
I disagree that these teams rely on Salah to win most of their games. It's in the nature of Salah and how good he is at the game that he scores most of the goals for the team. His contribution is bigger than that of others in terms of goals.
In my opinion Liverpool would still be the favorite for the title in the Europa League even if Salah was out for the rest of the season.
It seems to me that Liverpool will be more at the level of Bayer and Milan in this case. Salah for Liverpool is KDB for City and just recently we all saw how bad City is without KDB. But all this is just a theory, since judging by the news the injury turned out to be not serious and Salah will miss only two games. And by the way, if tomorrow Cape Verde shows integrity and plays Egypt seriously (despite the fact that they have already secured first place in the group), then Salah has a great chance of returning to the Premier League very quickly since Egypt only has two points and either Ghana or Mozambique could overtake them.