Well we can rule out Spike...who's already signed up for next season. We can rule out Angel, because it's his damn show. And we can rule out Fred, because she's only female member in the cast.
As much as it PAINS me to say this, I think IF anyone dies it will be Wesley, though I would rather see ANYONE die over fred/wesley (including anyone in the buffy story too). I read in an article with Alexis that when asked if a death was in the future he said that half the writers wanted to kill him and half of them didn't...but of course...he didn't say which side Joss is on...which would make the finale decision. But i don't think they will kill him off. As much as I love Wesley, besides Lineage, he hasn't had a real prominant role this season, so it wouldn't make sense. Joss has never offed anyone just to get rid of dead space (i.e. killed Jenny right when he gets back with Giles, killed Angel when he turned good again, killed Joyce right when she was getting better, killed Tara right when her and Willow get back together). Killing Wesley now would be like killing Cordelia in season 1. It would be pointless and wouldn't have a lot of emotion substance...well except for the diehard wesley-ites who have loved him from the beginning.
now...if he started dating fred and doing a lot of prominant things in the show....then i would be more worried, but right now i'm not.
notice how joss never likes to kill the CORES, just kind of the outsiders? Like in buffy...well wtih the exception of BUFFY (who came back) he never killed Xand/Will/Giles. In Angel, after loosing Cordy and Connor in 1 season, I don't think he will kill Gunn/Wes/Fred because they are the cores and it just would screw up this whole karma he's set up for 7 years.