That's possible. Xander has been taking one kick to the gut after another (losing his eye, Anya, Renee) and doesn't seem to be showing much reaction. He's holding a lot inside, and that can't be healthy.
He's been saying, going all the way back to season 6, how much he misses having male friends around to talk to. Now the two best male friends he's had... Riley and Oz... are both back, and probably on opposite sides of the Buffy issue. I feel sure that Twilight will try to use Riley to get at Xander and turn him.
If it's Xander, then hopefully he'll get an opportunity to redeem himself, and hopefully that won't require his death.
Scott Allie said the complexity of Xander's character story will be a close second to Buffy's this season. Since he hasn't done much of anything in the first half of the season, we can bet the second half will be a big one for him.