First of all Marner for 1 is at least a couple years from being an NHLer, he is still playing junior hockey, Kapanen will spend most of the year in Toronto with the Marlies cause he isn't ready yet to be a full time player. The only one who will probably be ready next year is Nylander so along with the other guys you mentioned there are still lots of spots to fill on this team..
Regardless, we will see what happens in July when free agent frenzy starts. I am only stating what I have heard, nothing is set in stone.. Toronto has all kinds of Cap space to sign these type players.. We will see in July who gets what players I guess...