Jaune will start taking an active role in the cult.
Frustrated at what his team (read:followers) have done behind his back and upset at the lines they could potentially cross, Jaune will seize to be passive and start being more active in how they operate to stop, or at the very least limit, the damage they could do.This could lead to both comical and scary situations where Ren, Pyrrha, and Nora either interpret his orders literally, follow his orders to the letter but not spirit, or straight up exploit the wording of the orders to do things he wouldn't approve of out of his (supposed) welfare.
The final say over who Jaune marries will fall to Salem
Salem is obsessed with Jaune getting hitched and giving her grandbabies, and this obsession is made stronger by being, you know, the Queen of Grimm and him being more or less an heir to her legacy. She thus possesses power beyond anything Jaune or the governments of Vale can do and would have the final say over the question of marriage.Pyrrha would probably be her first choice: besides being genuinely friendly, she has shown more devotion to both Jaune and the Cult than any of his other love interests. Weiss might be her second choice, both being devoted to Jaune and the daughter of an influential business leader, but not being a member of the Cult means any loyalty to Jaune could be compromised by devotion to Atlas, one of her major rivals.
Salem is going meet Weiss
She'll act like the combination of an indulgent aunt, a loving maternal figure, and an evil Grimm queen. She'll be all over Weiss about embarrassing childhood stories while also (subtly) threatening Weiss if she gets any funny ideas about breaking her nephews heart.