Something around Malkin vs Bergeron and Marchand could it be possible?
Pittsburgh get: the Crosby/Bergeron/Marchand line
Boston get: a Allstar #1 center
Who adds?
Pittsburgh adds. Boston already has a #1 all-star center in bergeron and a top end LW in Marchand. On top of all that it's been over 4 years since Malkin has played even 70 games.
Two things. First off, Marchand would have to come with a new contract (or at least be willing to sign one in PIT). But if he's willing to sign a contract in Boston, why would Boston trade a good top 6 winger and a great #2C for Malkin? They already have very good center depth with Krejci and Bergeron. The difference (for BOS) between Malkin and Bergeron isn't Marchand. And while PIT adds, it's not like they're overflowing with assets that they could add that would make sense for either side.
Secondly, Pittsburgh wouldn't get a Crosby/Bergeron/Marchand line, as they (just like Boston) need Bergeron to be their #2C. Bonino (who doesn't have a contract past this year - and who PIT would be hard pressed to afford if they had Marchand at 6-7m) who was great in the playoffs, is not a #2C. That HBK line was amazing, because he had an allstar winger in Kessel there. But as an every day thing, there's serious doubts among Pen fans that Bonino can play the #2C role full time.
So yeah, Boston says hell no unless PIT adds something significant (which they likely can't afford) and PIT says yes until they see what BOS would want them to add, where they'd then say hell no.