Rocky's son Robert Balboa Jr. could play a pivotal role in Creed 4, and his return is more important than Sylvester Stallone's. The Creed franchise continued various storylines from the original Rocky movies, but the focus of the series fully shifted to Adonis Creed (Michael B. Jordan) with Creed 3. The movie marked the first time that Sylvester Stallone's Rocky did not appear, as he remained out of the main story. This made sense based on Creed 2's ending, which reunited Rocky with his son Robert (Milo Ventimiglia). This has not stopped speculation from beginning about how Rocky could return in Creed 4.

https://screenrant.com/creed-4-rocky-son-robert-return-important/