Agreed. Not sure about Muzzy or Barrie? But a lot will have to do with the CAP and what both want. I have to admit I am biased for Muzzy.
To be very honest if we keep playing Ceci beside Rielly, we could easily increase his value by a lot.
Knowing that Dermott is likely going to excel in the top-4 (A hopeful assumption here, but whatever), we could play him beside Rielly where he could excel. Marincin would go back to his 3rd pair spot beside Sandin.
In return, we would get a potential 1st round pick (in a deep draft) plus the 4.5 million cap-space freed up, leaving us money to trade for whatever needed.
Start of season (till Dermott comes back):
Rielly - Ceci, Muzzin - Barrie, Sandin - Marincin
When Dermot comes back:
Rielly - Ceci, Muzzin - Barrie, Sandin - Dermott*
At the TDL, trade Ceci and promote from within:
Rielly - Dermott*, Muzzin - Barrie, Sandin - Marincin
It's a win-win situation. We don't get worse. In fact we probably get better by playing Dermott in an increased role and not just 12 minutes a night. The 1st rounder and cap space at the TDL is a big win.
Of course this is all assuming that either one of Sandin or Dermott excels massively.