laine just got Dubois. Gaudreau >>>> Laine
Even if Laine is worse than Gaudreau, this is trade value we are talking about, not "better right now". Laine has more years of control, has shown in the past to be a top level sniper, and both players have some glaring faults to their game. I don't think Columbus would have traded Dubois for Gaudreau.
Which brings up my next point. You were talking prospects, then flipped to the Laine/Dubois deal. So which is it? Are the Flames selling Johnny for picks and prospects, or are they looking for a player exchange? Because most of the discussion has been about prospects, but Dubois isn't a prospect, so... yeah.
In terms of prospect value, I'd say a late 1st (because it is the higher end teams that will deal a 1st), a good prospect (but not a blue chipper like Byram or Lundell), and either a 2nd round pick or equivalent prospect. And Calgary probably has to take a junk expiring contract back, or retain salary, which I don't think they ever do, just to make that work. We're going to see that a bit more this year.
Gaudreau being traded at any point before the draft probably won't happen.