We have likely commitments from btc38 and bter that they will be honoring the BTS split from PTS on the 28th. You will not be able to withdraw your BTS from these exchanges until after the BitShares XT network is finalized and assumed secure (not needing a reset). This provides an interesting option for people wishing to speculate on BitShares X during the testing phase.
We will be getting more information regarding how these exchanges will handle this prior to the 28th. So do not consider this an 'all clear' to leave your balance there, but do be on notice that this option may be available to you.