well, it seemed to me that at the end of 'swan song,' and by the end i mean when 'chuck' types up THE END to his story, that everything was well and wrapped up. then came the notion that nothing ever ends - and season six is born!
cliffhanger ending shows us dean going back to lisa and ben and deciding to make that 'thanksgiving dream' come true, because that's what sam wanted him to do. repeatedly throughout the season, sam and dean tackled the 'what if's' of the aftermath of the apocalypse and most of the ends they hit were less than favourable. however, 'dark side of the moon' opened their eyes to a look into each others' souls and dean saw that piece of sam's heaven - the thanksgiving dinner away from home with a real family. so i think dean really took it to heart when sam told him to get out and live his life. will the itch suddenly stop itching? no. there's always the urge to scratch.
so, the question then comes: does lisa get caught in the crossfire? or does she cross over to the dark side? frankly, to protect my son, i would do anything so i find it hard to believe that she would not get involved in some way - besides, the winchesters are dying out and we've lost so many hunters already. it's time for the next generation to start training. does she get killed during a mission and leave dean to care for ben on his own, effectively raising the next dean as he was raised by john? the next perfect little soldier following in daddy's footsteps?
and what about samuel? as long as we're talking about who's dying and who's coming back - 'in the beginning' left him dead, a victim of old yellow eyes. now he's rejoining the cast of hunters? [at least they're bringing back mitch pileggi to reprise the role] the interesting part will be how the group flushes out over time - and this could very well be the out for lisa. maybe she just decides that she could handle dean's past, but she can't handle sam*2. bringing grandpa back into the picture adds a few little details that shouldn't necessarily be overlooked. [a] he's one more hunter, an accomplished one at that, so maybe dean doesn't have to turn his life completely upside-down. [b] he just came back from the dead! and if he can come back, anyone can, right? so why not lisa and/or ben? [c] if god's bringing back hunters, there has to be something to fight, so maybe dean will have to bring lisa into the fold if she wants to live and she wants to protect her son. [d] if sam's back, and lucifer is defeated, who is running the demons? crowley? we haven't seen him since his deal with bobby and chicago vs. death in 'two minutes to midnight.' he could have a lot to say... and a lot of hate and discontent to stir up!
so what do i think should happen to lisa - she should become a hunter and die that way, if at all. is she good for dean? who are we to get into someone's relationship? oprah? dr. phil? i don't really care, as long as it doesn't hurt the overall story. just remember: from here on it's all gravy.