Season 1 Steven and Star both acted like they had ADHD and needed a straight man to reel them in, Beach City turns out like Ocean Town.
Characters wise, Steven develops more of an inferiority complex until he starts gaining powers but even his powers look lame compared to the bullshit Star can do so who knows how he'll develop, Star matures faster with the influence of the Crystal Gems.
Ludo and his henchmen get killed by the Crystal Gems, Toffee's plan probably fails at the start and he gets bubbled or something, rest of the Star Vs villains get beat without much of a problem. Jasper and Peridot get bubbled in their first appearance. The big questions are 1. Do the Crystal Gems still find out about the cluster and 2. Do the Diamonds still find out about Steven. If the Cluster hatches then Steven and Star would have to flee to Mewni while the earth is destroyed, show ends with Steven and the gang living their lives in Mewni and the Diamonds still ruling our universe.