If you resign both Lyubushkin and Giordano, realistically, Holl is now your 7th or 8th defenseman, and you're not paying 2 million to someone who isn't going to be a regular. Not to mention, saying Holl has been excellent away from Muzzin is a pretty big overstatement. Has he been better, yes, excellent, definitely not. His decision making is very slow and he tends to hold onto pucks way to long which tends to keep us in our zone much longer then we have to.
Giordano and Liljegren have been a excellent pairing and would definitely look at keeping that pairing even next year. Rielly and Lyubushkin look great together as Lyubushkin brings that defensive minded partner for Rielly which he has always needed and gives Rielly that protection to be more aggressive offensively. That now leaves you with Sandin, Muzzin, and Brodie which I take all 3 over Holl easily. Muzzin has a NTC which I doubt he'd be willing to move considering he's near the end of his career and I doubt he would want to be moving his family away for 2 years considering he's from here.
Rielly-Lyubushkin
Giordano-Liljegren
Muzzin/Sandin-Brodie
Muzzin/Sandin
Moving Holl for picks allows you to use his 2 mill cap towards resigning both Giordano and Lyubushkin.
Holl Stats, D pairs with minimum 50 minutes of play time together:
Dermott - Holl: GF% 100, xGF% 46.35 (only 53 minutes though)
Sandin - Holl: GF% 66.67, xGF% 51.95 (this and above are the two best on the team actually)
Brodie - Holl: GF% 54.55, xGF% 58.24 (same usage as the Muzzin - Holl pair)
Muzzin - Holl: GF% 41.46, xGF% 53.61
Muzzin - Brodie: GF% 42.86, xGF% 53.86
Muzzin - Lily: GF% 50.00, xGF% 47.84 (the only player Lily has an xGF% below 60% with)
The real results are terrible for Muzzin. Depending on you belief in xGF you can argue that Muzzin has underperformed his xGF% stats, but for me the eye test shows Muzzin xGF% is inflated by the teams puck control and the inability to quantify the extreme high quality chances he's giving up with frequent bad reads and poor neutral zone play.
All that said, I get the desire to replace Holl with Bush, it wouldn't be my personal choice but can see where people are coming from there - having a more physical and aggressive player in that role is reasonable. But that's not really 'saving cap' so to speak, you're just replacing Holl with Bush, I can't imagine you can resign him for much less, or less at all than 2 million. That's a more expensive D-core than we went into this season with, even if you have Gio signing for league min.