Leafs fans have already said that Marleau has told management he's not interested in playing C. I don't follow Leaf news closely enough to know the validity of it but I'll take their word for it.
Also not sure what having 2 1Cs has to do with it? Its just about moving your best winger down to the 3rd line to fill a C position. Seems like poor usage of assets where you might be hindering the productivity of one of your most dynamic offensive players.
It means you take away that 3c, and its really irrelevant they still have top 3 center depth in the league.
Nylander/Marleau are potential options, johnasson I think is a center, they can always trade for a rental 3c.
I think Manson would improve TML at their 1RHD position(imagine him playing with Rielly) a lot more than kadri at your 3c... not a shot at kadri(I like him a lot) but they have more than enough weapons offensively, and I they can pick up a top 4 RHD on a solid contract for the next 4 years without giving up their top 4 offensive players, and keeping their 1st and top prospects... there is literally no way they don't do that. Specially with dubas at the helm.
Despite what I think kapanens trade value is, he will be a solid NHL'r when he gets his chance, and I think johnsson will be a serviceable 3 or 4c at the nhl level... the leafs still have a few prospects up front that can easily jump into their bottom 6.
Not saying Anaheim would do it, tho its much closer in value then a lot of trade offers we get for manson.