Yes, Atalanta's chance to get a place in the European zone is still very open. Especially now that they are starting the season very well compared to other clubs. I think if they are able to maintain the current state, finishing in the Champions League zone is not impossible even though their opponents are now quite tough. The key is they don't lose points if they face a competitor for that spot.
Atalanta's chances of getting to the UCL next season may be tough, because this season the top team in Serie A has show us their good performance. However, we still don't know for sure how the team will perform in Serie-a in the next few weeks. Whether they can stay consistent or not. If there are 2 of the top teams in Serie A who are inconsistent while Atalanta manage to show their consistency, then Atalanta can have a chance to be in 4th position in the final standings.
Last season they failed because they couldn't make a good rotation when their schedule was tight in matches, now it's a different thing because they can freely and focus only on Serie A while other clubs have to think about the league and other competitions.