As others have said, I think it will be difficult to get a mutually acceptable value for both sides. Leaf fans will rightly point to his on-ice play thus far and his handedness, in addition to his draft pedigree+AHL performance to show this is not an aberration. Opposing fans will point to his limited role and will want to see more before offering up significant assets.
One thing I will add, though, is that Liljegren is indisputably an NHL defenseman -- a #2 defenseman or #6, to be determined -- and that outcome is a damning indictment on many of those who proclaimed him to be a bust. I'm not talking about opposing fans, but certain reporters and anonymously sourced GMs who for the past several years were insistent that his development was disappointing, in stark contrast with what Marlies watchers were reporting.