Every team has question marks heading into the post season, but I would set our lines as:
Sedin - Sedin - Kassian
Raymond - Kesler - Burrows
Higgins - Roy - Hansen
Sestito - Lapierre - Wiese
Schroeder
Hamhuis - Garrison
Edler - Bieksa
Ballard - Tanev
Schneider
Luongo
My reasoning for Kassian with the twins would really depend on the matchup. The issue with the Sedins in the playoffs is always a lack of time and space, which the opposition has shown they can take away from them quite easily, especially when facing a Norris type defenseman in Suter or Pietrangelo.
If we play Minnesota, having Kassian with the twins could really make Suter have to focus on dealing with a big body like Kassian and give the twins more space. They also need some protection out there so guys don't take liberties.
You always have the option of going back to Burrows with the Sedins as well if it's a less physical matchup. For example, against the Sharks or the Red Wings you could stick with Daniel, Henrik, and Burrows.
I just like the idea of Kassian banging and crashing and making the other team's top defensive pairing always needing to have their head up and know they're going to get hit hard every time the puck is sent into their zone when they're on the ice.
Now, this is all based on Kassian showing some consistency, which remains to be seen.