From what my sons neurologist said it may very well help all of them . If it helps one category there is no reason to believe it wont work for the others . That was a comment he made about 6 months ago at our appointment .
Exon skipping can help those with point mutations, however it will depend on which exon it is due to the way the exons fit together aswell as if that exon codes for a critical part of the protein.
Also exon skipping is currently only being evaluated on the most common exons that need skipping. The hope is that with enough data acoss various exons skips they will be able to personalize the skip to suit each individual.
Is you point mutation creating a stop codon? There is also ataluren which i about to start some phase 3 trials shortly.