Worf might have more overtly replaced LaForge at the helm when LaForge got his gig in engineering.
But that's where they wanted Wesley... for a while anyhow
I'd expect that it would've made it tough to develop Worf the way they did. Frankly, the best thing to ever happen was for her to leave, it cleared room for him to be featured, & in doing so, opened up an entire story arc, that while some people can take or leave it, I found it one of the most engaging things about the show. The houses of Mogh & Duras, K'mpec, the high Council, K'ehleyr, Gowron, Kurn, Romulan collusion, revolution, etc... If Tasha stays, you might not have gotten all of that, maybe some, but much less.
Ultimately, Trek explores characters best, when they have an alien culture to explore with it, the very same way they did with Spock on TOS. That's what Worf brought to the table, an entire culture to explore. The only other Alien species in the main cast was Deanna & they sure as heck weren't interested in fully exploring Betazoid culture in the same way. Of course there was also Guinan, & Data who weren't human, but weren't really a whole culture to represent either.
Nope, they were far better off having reworked the Yar concept into an alien named Ro Laren. That type of tough badass thing is really all they could've ever hoped for with the Yar character anyhow, that & a one off romance now & then. Look at the treatment her character got in Yesterday's Enterprise. I like the episode, because of other aspects, but her part in it was a big yawn. Honestly, I don't think Crosby was right for the part they wanted anyhow, the tough badass security chief woman, escaped from oppression & rape gangs etc.... She didn't really play that aspect very well at all, which is why I'm sure all parties weren't comfortable with what was coming of it. Michelle Forbes gets it. Nails that dynamic big time. She just exudes "Don't F### with me!", Crosby? It was more like "Gee, don't you feel sorry for how hard I've had it?"