If the Sabres end up with Ekblad, I'm not all that worried that there won't be a D for F trade out there; young forwards of the ilk the Sabres would want get moved almost every single season. Obviously the concern would be making the right deal but that will always be the case.
Additionally, if the Sabres end up with Ekblad, time is still on Murray's side. There would be no immediate pressure to move anybody until the deal he wants comes along. Heck, even if Ehrhoff wants out and that gets accommodated, there can still be another deal centered around one of Myers/Ristolainen/Zadorov/Ekblad/Pysyk*/McCabe* out there somewhere.
*I'm of the opinion these guys wouldn't be centerpieces of such a deal, but for these purposes I'm lumping all the desirable defensemen together.