Until Hutson is NHL ready, I don't see the left side changing much with Matheson, Guhle and Xhekaj as primary LD. As for RD, it'll come down to who grabs which spot. I don't see Savard, Barron or Harris here much longer. Savard is slowing down as you pointed out and Barron/Harris just seems to be a 3rd pairing guy. Would much rather give ice-time to the queue of higher skill-ceiling behind them than play them for the sake of keeping them, only if those players are ready.
Ideally, I would love to see Reinbacher and Guhle paired together, as I see them spending many seasons paired together. I would love to see the addition of a younger Savard-like RD acquired to slot in beside Hutson in the long run, or that's possibly what the Xhekaj RD conditioning could be about as well. I want to stay cautious about saying Xhekaj being a staple top-4D, realistically he will probably top out a bottom pair Gudas-type guy, but still holding out hopes
I really do see in the next 2-3 years a tough decision being made between which 2 of Matheson, Guhle and Hutson to keep. From a management standpoint, it's a great problem to have.