If SMG is Buffy... Yes in a heartbeat. I even wrote my own version.. it's called Buffy Jr On The Run. It would've been about Buffy's daughter JR who would be the next Slayer in line. Since SMG didn't want to be in BTVS permanently, she would've been more like a memory that lives on throughout the tv show/movie...

As much as I love Lisa and Ben for Dean. They were irrelevant most of the time. Whether they come back in season 16 or not. Their storyline won't make sense, in a way...I do hope they come back.... but Supernatural has nothing to do with them, so no matter what, they better make another season...