Good question!

To be honest borrowing from 6.01 I imagine it wouldn’t wake her in the real world, but Belle would have woken under the curse. She would still be trapped in the dream world but she would be aware that’s where she was. Basically the true loves kiss would do half the job – wake her mind but not her body.

If this scenario had happened, once Rumple got past the initial NOT POSSIBLE shock. He would leave the dream world and kiss Belle awake completely. So the story would have played out much the same, except Rumple and Belle would have had a chance to talk before the confrontation with Maleficent and Belle’s loved ones.