You know, the way Bishop Williamson (and the true traditional Catholic cause) is being treated by the SSPX leadership, I'd say there could be a split in the SSPX no matter WHAT happens on September 14.
Maybe the reason there hasn't been a split is because +W hasn't been kicked out yet, and he's a good obedient man?
But if a false agreement were reached, +W would be forced in conscience to act, and not go along with it. That's when the masks would come off and he'd be kicked out, encouraged to quit, etc.
Then they'd have their split. That's actually the only way I ever see an SSPX split happening.
DIVIDE AND CONQUER