Flames fans...

Would you want the proposal to take out Mathias Emilio Pettersen, 2nd & 7th round pick and instead you add Dillon Dube?

Seems like a fair proposal. Only problem if Eichel for a long term this season, the Flames probably aren't in playoff contention.

Swap Mangiapane and Dube for the lines. I don't know why other fans think Dube will be higher than Mangiapane

I would move Dube before MEP and picks. If you look through the Flames prospect pool there is a lot of mid - top 6 left shot forwards, all guys that likely don't get a shot on the fourth line cause you don't want them getting ran over all night so moving a guy like Dube opens a spot going forward for a Pelletier, Zary, MEP etc.
Another piece to that is that if the Flames are trading for Eichel to me that signals that they don't care about winning this season, he likely doesn't play for most of the year so the Flames would be down to Lindholm, Backlund at C, next season when he is back though you want to have a strong line up with those prospects breaking camp in middle 6 roles.