Trading Marner would be a lateral move as he is excellent offensively.
I just don't see the point really, the league has shifted and shown us that you CAN win without spectacular d and with great offense and we have that in Marner.
I also do feel as though he has Kane like upside (even better defensively already) and he is a hometown boy which is another huge plus.
I'm sure all the teams are happy to keep Provorov, Werenski, Ekblad, Parayko and Slavin and would tell us to f off anyways, but I'm not sure the Leafs would do it either. Not saying I would be hyperbolic and say "LMFAO NOT EVEN CLOSE, ADD 3 1sts AND MAYBE YOU GET MARNER'S COUSIN," it would be the politest of declines ever, but I just don't think it's as crazy as some seem to be suggesting in wanting to keep Marner over "potential" future #1 dmen.