In a vacuum I would probably make a Mikko for Rantanen trade, because I'd rather allocate those dollars towards a 2nd line center instead of a 1st line winger. HOWEVER, that cannot happen by also including Bo Byram and Cal Ritchie.
I think MacKinnon and Pettersson as a duo would be more than capable of finding success with Nichushkin/Lehkonen/Drouin/4th winger to form a great top six.
I'm on the fence in a vacuum scenario, but on top of all the better offensive seasons from Mikko, and his chemistry with Nate, we can't ignore that Petterson is going to cost $3M more than Mikko next year.
They're probably going to have to lose one of Girard, Byram, or Manson in the offseason as it is with Mikko at $9.25M.
With Petterson supposedly still sitting on a $12M offer from Vancouver, that price would mean they'd have to lose somebody else like Lehky, or they'd have to lose 2 of Girard, Byram, or Manson and replace them with someone worse.
A $12M 2C will significantly impact the Avs depth at both forward and D, and they will still have to keep going with cheap goaltending. It's just a luxury I don't think they can afford.