Ugh I know this is real life and not NHL Be a GM but I would dangle future picks, other prospects.. anything before Mercer.
The dude is a stud, under cost control for a long time, and has just... everything you want to see in a young player. It certainly wouldn't be a lateral move by any means, but I think the addition of Meier by the subtraction of Mercer would be far less beneficial to this team than we think.