As much as I want to see Kendall go evil and have Sydney go after him, I'd really like to see her and her mother in this race to kill each other, maybe them fighting together sometimes. I think it'd be cool. Mother vs. Daughter, who would win?
i think it will remain the same ones with new ones thrown in like always, but the main three will be irina, sloane and sark(i do think in that order too!)
i think it will remain Sloane for probably the entire run of the show. he really is the villain. i think Irina will be a real Villian eventually if not already. and of course Evil Francie is an enemy, but she is working for THE enemy so i don't really count her. but i don't count out the possibility of them introducing a new character.