If they appeal, they'll be on the line to lose even more (and Epic is itching for this fight to continue, so Epic might appeal). Apple can cut its losses and be happy with the current, quantified ruling, or roll the dice and possibly run into a terrible precedent for other jurisdictions that have been rattling their sabers at Apple.

Epic will need to appeal, they are still not allowed in the App store for breaching contract, this ruling did not change that.

They need get favorable ruling on appeal taking the view the contract was not valid and had illegal terms therefore Epic was not in breach.

Without that Fortnite is still not returning to the App Store.

I expect both Apple and Epic to appeal.