i got a feeling that the way Ruby was wording it (very carefully by the way) that it could be applied to either Lilith or Sam, sort of whoever is the last one standing is the one who opens the seal..

im convinced sam killing lilith is the final seal, but i bet ruby is gonna make sure sam is strong enough to do it so it wont have a chance to "whichever way it goes" she'll make sure he wins.

I'm positive that Ruby's been manipulating Sam all along so that he will kill Lilith and I think the very act of Sam killing Lilith could be what opens the seal. Or Sam drinking so much blood in order to kill Lilith turns him into a demon and that's what breaks the final seal.

personally i think that lilith is the last seal...and like fanfly said, i think that ruby has been playing sam from the start...why would she care so much about lilith's death...lilith has done nothing 2 ruby, so again why does she care?....remember last episode ruby said something about the second in command breaking the last seal...me thinks it was yellow eyes and since he is dead, that second in command becames sam.

I truly believe that Ruby is on the same side as Sam and Dean, but we will have to wait and see. It is possible that everything she has done in the past two seasons has just been the lead up to this, and she is actually on Lilith's side(which would suck, and her popularity rates would drop profoundly) BUT Ruby may just want Lilith dead for everything she has done. But also, the idea that Sam killing Lilith is the real final seal, and then Sam will free Lucifer is a good idea, and does have some backup. But I am choosing not to believe it (sorry!) and I want to trust Ruby, and believe her when she says that she wants to help Sam.

I'm not sure i think maybe twisting Sam into a full blown demon is the last seal. But one things for sure Ruby is a sneaky little bitch and i'm more sure than ever that she's evil!

I think I agree with fanfly! ♥