Or if rejected...
...the Sunnis have shown they will not be bypassed in the constitutional process. They will go back and wrangle more and show at least some token respect to the Sunnis in order to get them to pass the next constitution. Long-term, Sunnis feel more enfranchised and become less likely to revolt - maybe end up with a constitution they actually like better.
If I were a Sunni, I would be very skeptical of the recent "O yea, let's make it so we can change it later if we want."
Not really arguing for this as preferable. Just saying I can't tell which from the alternatives will end up with better chances.