In total all of these trades are biased towards the Leafs and most likely won't come to fruition.

The initial trade doesn't even go through. Gardiner is arguably the Leafs best Dmen. Gardiner outscored Duchene last year. Gardiner is cheaper than Duchene. So why would the Leafs have to add so much to obtain Duchene?
They don't.

All of Colorado's players had bad season last year. Also Duchene is 26, while Gardiner is turning 28. I wouldn't say that trading Gardiner is a good idea, as you have no replacement for him in an already weak defensive corps. Also leafs don't need Duchene, as they are already stacked at center, and neither does Philly. They have Giroux, Patrick, Couturier and Filipula who can play center as well. Also giving up Konecny and Sanhiem, both whom are marvelous player is too much for Duchene.

6 months is big age diff considering the position they play. but gardiner cant fetch duchene. ur creating a massive hole in an already weak d core
You can see the bias in this comment. Duchene turned 26 in January 2017, Gardiner turned 27 in July 2017. Gardiner is 6 months older than Duchene and you're making it seem like there is a 2 year gap.
I don't think Toronto does the first trade as Duchene has underperformed and at this point its a risk in taking him on. He would also have to outperform Kadri for the #3c spot (which he didn't last year) because #1 and #2 centre are reserved for Nylander and Matthews. (Im also not saying Colorado would do this trade, I don't think it helps either team. But many are writing off Bracco who has Top 6 potential at least)
The Philly trade just doesn't fit with Phillys likely new build around Patrick.
If JVR gets signed to a 6x6, the Carolina trade is possible if the leafs add a bit more. As it stands now, Hanifin wouldn't get moved for that cheap.