In that case Milan end up 5th, Inter 3rd, Atalanta 4th.
But that's much less possible than the scenario where Atalanta, Roma and Milan finish on same points. If we beat Atalanta, while Roma and Milan win their remaining matches and Atalanta win their last match, then all three will end up on 68 pts. In that case, Milan will win the mini table and go to CL as 4th placed.
Actually, that's what Milan are hoping for and that's why they already started talking about it:
https://www.football-italia.net/137988/donnarumma-hopes-juve-favour