Mathematically, this is unrealistic. This is far from 4-5 games. 4th place averages 65% of possible points, which is almost 2 points per game. So if Juventus play perfectly and always take three points and all other teams play as usual, then Juventus will need 13 games to get to fourth place. At 17 games it looks sort of possible, but I think you'll agree that it only looks realistic in theory.
Yes, it's just a matter of calculating the odds, which are certainly very different from what happens in the field.
But if Juventus can wipe out all the remaining games they have then they will be in I think. But can they do that? to be honest personally I doubt they will be able to get a perfect win from the 17 matches they played.
Even if we assume that Juventus will be the clear favorite in each of the remaining 17 matches and the chances of winning it will be a stable 1.3 (this is a very bold assumption since the away game against an underdog gives the worst odds), then the probability that Juventus will win all the remaining games will be around one percent. That is, you can expect such an event once in a hundred years. Well, if you take real odds, then even much less often.