As perhaps you realize, RD's are at a premium in the NHL.I mean I really like Koivunen a lot but he was ranked #7 in the Canes system at the time of the trade last year. I would argue that all of Nikishin, Nadeau, Morrow and Blake were better prospects than any of the pieces Carolina gave up. Plus they didn't have to give up a 1st in the deal, although the Penguins getting Brunicke with that pick makes that not a problem.
I don't think what worked in the Guentzel trade last year will generally work when bidding for most top players. For example, you're probably not pulling off Miller without including one of Morrow or Nadeau.
IMO the Canes could get Miller with something like Kotkaniemi, Morrow and a 1st, but I don't think we've seen a track record of them trading a prospect on par with Morrow.
Re: Canes roster-Burns has aged out (buyer beware for the team looking to sign him next year as his play is meh this year) and Morrow is a RD that is getting good experience in the AHL this year .
He is slotted as a likely candidate (low cost too which helps filling out the roster) for next year's roster. With the marketplace rejecting Miller and prices offered reportedly very low, there is very little chance a shrewd organization like the Canes would offer effectively 3 firsts for Miller.