Wow, nice trade. If WSH is gonna go big like this, I'd like to see them acquire a D as well.
There isn't a reason for the Capitals to pick up a D unless it's to replace Orpik (which then means finding some poor chump to take Orpik). The 3rd pairing of Orlov-Schmidt has been fantastic so far and they have a plethora of D prospects who will be ready in a year or two.