Yeah, they completely could. Except, God, I hope they don't. Already just having them not constantly in scenes together is breaking my heart. *little whimper* Where's the LOVE?

I think whenever I need a LOVE episode, I'll rewatch Bad Day at Black Rock. Love and cuteness. (You're right; it was epic.)

On Sam and Dean as enemies: It might be fun to explore--as long as it's corrected very soon after. My favorite eps tend to include one of the brothers "turning" on the other: Skin, Asylum, BUaBS (and John in Devil's Trap). It's just a really interesting dynamic. Though, no, I couldn't handle it as an extended plot arc either. :(