If she had stayed they probably would have made Worf chief engineer and I think that would have beenb much more interesting than his security job.
Actually I think it more likely that he'd have ended up at the helm. I think they were wanting Geordi elsewhere even before they moved him there. His featuring at the helm & in command roles didn't seem to stick much
It would have been very interesting to see Worf at the helm. Encounters with, say, the Romulans, would have gone very differently, what with Worf being tempted to kamikaze the ship.
Picard: If the cause is just and honourable, they are prepared to give their lives. Are you prepared to die today, Tomalak?
Tomalak: I expected more from you than an idle threat, Picard.
Picard: Then you shall have it. Mr. Worf.
Worf: Aye, sir! Today is a good day to die! RRRARGHH!
(Fires up the impulse engines)
Picard: Do not engage! Mr. Worf, do not engage! (merde)