There have been a lot of guessing and rumors on this board regarding this....that's part of the fun of these boards anyway.
So far, we have a lifeguard that says the SAB pool will be for Y&BC and BCV only after BCV open up. Others have suggested this as well.
So far, the only pool that has restricted pool hopping for DVCers is the AKL pool, which does not have DVC homes. Oh, and DVCers cannot pool hop on some holidays and any time the "pool authorities" determine they are at capacity.
I often hear on this board about how crowded the SAB pool is and that is probably what is fueling the rumor.
Bottom line, nobody really knows for sure. I could see DVC using it as a selling tool for the new BCV's....."If you join here you and these two resort hotels will be the only ones able to use this cool pool" (assuming your staying at the BCV, on your own points, and we don't change our minds anyway).