On 16th August, if there is no enough pre-buyer, what's the result of the remain pre-mine sys coins? Whether the pre-buyers or the miners will share them? Thanks.
On August 15 panic buying till the presale is sold out. If that doesn't happen they will only mine the amount sold during the presale.
That is correct.
From the OP
Q: What if the presale doesn't sell out? Do buyers get the unsold Syscoin?
A: No, only what is purchased will be premined and delivered. Buyers get what they pay for.