I think the season 1 finale would have been different if they had been renewed for Season 2. The finale definitely wrapped up the series and doesn't make sense for a season finale, just a series finale. So let me start with how I think the season finale would have been different:
After Anastasia is revived, her touching reunion with Will is interrupted by Alice, Cyrus, and the White Rabbit rushing in. They explain that they went to check on Jabberwocky and found that she was missing. We then see the Jabberwocky, free from the Vorpal Blade, in a mysterious, half-destroyed mansion, talking to two silhouetted figures and asking them what they want her to do. The older one looks to the younger one and says something to the effect of, "What do you say, Drizella?" as the lights hit her and reveal her to be Anastasia's mother. Drizella smiles and responds, "Let's destroy her."
This, of course, sets Season 2 up with Lady Tremaine, Drizella, and Jabberwocky as the main villains, in a similar vein to Season 7 of the main show with Victoria, Ivy, and Gothel. The main cast would be:
- Alice
- Will
- Cyrus
- Anastasia
- Tremaine
- Drizella
- Jabberwocky
Cinderella would not be Ashley -- even before Adam explicitly confirmed Anastasia was not Ashley's stepsister (and we met Clorinda and Tisbe), the timeline did not line up. This alternative Cinderella would be a recurring character seen only in flashbacks. The White Rabbit already had a largely secondary role to the plot and would be demoted just like Archie/Ruby/Neal/Will/Robin on the main show.
Jabberwocky would split off from Tremaine and Drizella early on, playing a role similar to Rumple where she helps both the villains and the heroes depending on what serves her own purposes. We would see flashbacks of her building up to what exactly she is planning, possibly also giving her a love story -- perhaps the person who originally trapped her with the Vorpal Blade was her lover? Around the time she leaves Tremaine and Drizella, the Caterpillar begins to take a larger role, still seeking revenge on Will and now Alice and Cyrus, and working with Tremaine and Drizella to accomplish this. As the series progresses, we would also eventually find out that Drizella has Lady Tremaine's heart and is controlling her, having been trained in magic by Cora just like Anastasia. Towards the end of the season, Anastasia attempts to save Tremaine and recruit her to their side by returning her heart, but it's revealed that Drizella cursed Tremaine's heart with an Enchanted Candle and she uses it to save the life of... idk. Someone. Can the Enchanted Candle actually revive people, or just save them from the brink of death? Cuz if it's the former I could see them temporarily reviving Cora or Jafar.
Flashbacks would focus mostly on Anastasia and her Cinderella story, of course, but I could also see them showing more of Alice's early adventures in Wonderland such as her early encounters with Cora and Ana, maybe we could actually see Penelope and how Will and Ana first met, and there would be flashbacks for Jabberwocky. I'm not sure what exactly we could see for Cyrus. Maybe he could have encounter Jabberwocky in Agrabah at some point.