So far, Napoli looks like a more realistic contender for 4th place, but the fact that Bologna will be able to hold on to this position for a long time looks doubtful. Inter, Juventus and Milan will most likely not miss their places in the top 4. In the next round, Napoli will have to play with Roma and if they lose, their position will worsen significantly. Atalanta and Fiorentina also do not look like those teams that are ready to fight for the Champions League zone. From 8th to 4th place the teams are separated by only 3 points, so all these teams have a chance.
Bologna just got it after winning over AS Roma in the last match day of Serie A. From Bologna to AS Roma, from fourth to eighth positions, there are only 3 point difference and there are five clubs are fighting to get that position in a next match day. They are Bologna that will have to defend the position and four other clubs: Napoli, Fiorentina, Atalanta and AS Roma.
Bologna are playing well and the position is a recognition for their good performances but with big challenges from other four clubs and with their limited power, it's very difficult for Bologna to defend that position for a long time.
If we look at Napoli's recent performance it is not looking very good. They keep dropping points here and there while Bologna just beat the top team, Inter Milan. Bologna's performance is too good at this moment to ignore. Napoli just lost 4-0 against Frosinone.
Napoli has an upcoming match against AS Roma and Bologna has a match against Atalanta next week. Bologna is currently 1 point ahead of Napoli right now. That win against Inter Milan is going to make Bologna more confident. I think Bologna is more likely to finish in the top 4 than Napoli is. Napoli has the players and class, they need to bounce back really fast from these defeats if they want to play in the Champions League next year.