This is a very good contract for a good player that absolutely improves the team.
However, I'm not sure that it changes the dynamic of what this team is: a very good first line (pick 3) and then a committee of above-average-to-good depending upon how some of the young players develop behind that first line. Playoffs-wise, if you can successfully shutdown that top line or force Nashville to dilute their strength across multiple lines, do they scare you? I'm not sure. They certainly might- and I certainly hope so.
That strategy worked for St. Louis and before them as well. I'm just partial to the higher ceiling offered by employing by more aggressive approaches.
Of course, that could still be a path if Trenin is included in any potential deal, but I don't find it remotely likely at this point (and not really before this signing either given the history).