No shot Carolina does that

Not enough. Necas's highest point total is 71 points. Marner almost achieved that in his rookie season. Canes will have to add multiple prospects and a 1st.

Why not? Necas is a 25-yo arb eligible winger who needs a contract in a down year after having a breakout season last year. He's still 2 years away from FA, so the Canes could go with 1-year deal but they would probably be better off giving him term now or trading him because either he'll cost a lot more or lose a lot of value. If they aren't comfortable with giving him term, then they should trade him (they probably get a 1st+ 2nd or 3rd at best). Getting Marner for him and two 2nds is a relatively tame price especially if they know they can extend Marner in the off-season.

Carolina won't give him that contract is the main reason. Not saying it is bad value for Marner just don't see Carolina as the team

That's fair but they might not need to since 10.25-10.65M in CAR is about equivalent to 12-12.5M in TOR. That being said I think they will manage to extend Guentzel, so unless they are getting another team to retain on Marner or dumping someone else like Kotkianemi. The trade doesn't help the Leafs improve anyways just gives them like 4-5M in cap.

Think about how many Marner jerseys will be sold once all the pressure of being a leaf is off him and he puts up 120 pts in Carolina. I think ownership would consider Marner an investment.