Andrei Kostitsyn is gonna score 35+ goals the moment he plays with a capable #1 center (which excludes Plekanec and Koivu). Sergei is developing into a nice two-way forward. While neither are power forwards, they're certainly not soft as a lot of people on HFboards make them to be. Both have to perfect their consistency, Sergei in particular, but they're certainly not the only young players having this problem nor is it something that can't be fixed.
Ryan McDonagh is a blue-chip prospect on the blueline. Good size, good skating, good hockey sense and some grit. He has what it takes to be a 1st pair defenseman, although top 4 is more conservative.
Patrick Marleau is a PPG player - in his good years anyways - who doesn't show up when he's needed the most.
I'd give Higgins, O'Byrne and a 2nd for Marleau. At the very most.
And Hodgson is going to score 50 goals per season.
Marleau is a very good player and re-established his value very nicely this past season. But asset-wise, he's only a 1-year asset to any prospective new team, and thus there is no way the Habs should give up anything of worth to acquire him.
Kostitsyn alone has greater asset value to the Habs than Marleau would, even if he's a significantly inferior player at this point. The Habs don't have the depth and aren't good enough yet to make one of those home-run swing all-or-nothing kind of deals for a short-term return.