Shattenkirk is going to be a busy man the next few years when he signs with the Rangers, Bruins, Leafs and Devils. How is that going to work when one of these teams is playing another? The team that trades for him before the ASG will probably have triple the odds of signing him long-term than the next closest team.
If the Leafs were allowed to set up the framework for an extension prior to a trade, I would absolutely be holding out for Nylander, even if it meant taking back Michalek and adding another "+". If we're talking about the Leafs simply taking a leap of faith and hoping he would be open to re-signing, I think a Shattenkirk for JVR swap is about the best these two teams could do and I would hope that the Blues would look elsewhere.