From the initial 500 th, assuming almost all GPU miners have changed scope to other coins, if you divide 6900 Th to 0,82, that an A3 can hash, there are already 8400 A3's connected on network. Maybe I'm wrong, but this is how I see the matter...
looks like the estimate is relatively accurate
here's a snapshot of the current status of mining siacoin w/ an antminer a3
It will bring the time between blocks to 10 min average, by counting the number of blocks since some date in the past (genesis block maybe?). Sia is still ahead of that and that's why it's throttling blocks.
