That both disappoints and puzzles me, in fact. If the cake had left her out cold in bliss wonderland for a couple days, then at least it would have had some form of tangible payoff and I would have been willing to believe that the escape was indeed over.
I guess Oda's two biggest intentions with the cake was (a) to write the last chapter in all its glory and (b) to show us again Sanji's cooking principles and feats. It was a good read.
Meawhile, the cake has worked as a way to take Big Mom out of the way and to save Totland. Not useless at all. And who knows if there will be further implications.
But, Oda just dropped a fully-charged Big Mom back into the equation and so something has to happen to stop her from catching up. The Straw Hats couldn't distance her when she was half-starved and brain-dead from her cake obsession, I don't see how they're going to when she's back at full strength and clear-headed. I know she's supposedly too far away thanks to Chiffon's insistance on luring her to Puffs island, but seeing how relative distances and ship speeds can be in this manga I'm not really buying this as a satisfactory explanation.
So, escape not done and I expect we'll still need one or two chapters to completely wrap it up.
I don't think it's a matter of what would make the most sense, but of narrative feeling. For me, at least. Big Mom will arrive at Cacao Island only to decide her next move, maybe heading to Wano.