As for Dybala, the worst possibility is that he will not recover in the near future. but there is no certainty regarding Dybala's injury, for sure there are several options to replace Dybala if he is confirmed to miss the Qatar world cup.
Dybala is not a core player, he is rarely a main starter, but his presence is still a good choice as a second-tier player.
I don't see this as a real threat to the Argentina squad in the Qatar world cup later.
How can you say that Dybala is not a core player? He maybe a bit underrated, but IMO he is an integral part of the Argentine national football team. And from what I heard, his injury is quite serious and it may force him to miss the world cup. He is just 28-years old and maybe able to participate in the future editions of the world cup, but this time it was a golden opportunity for Argentina to lift the trophy. Still, I am expecting a miracle. We have some 40 days to go for the world cup and all we can do is to keep hope.