In an interview with Collider.com, Savage Steve Holland (Better Off Dead...) said that he is directing the next two Legally Blonde sequels:

I heard that you were directing a sequel to the Legally Blonde franchise. Is that true? And what's the story about? And when do you start filming?

Yes, it's official, I am directing the Tri-quel to Legally Blonde. It's called Legally Blondes. I'm not sure how much I can say about it as I just got the call. But it's very sweet and funny. Beloved director Sean Macnamara (Bratz) was supposed to direct this project. He had too much on his plate as a show-runner/producer. His company Brookwell/Macnamara basically produces EVERYTHING else that's being made in this town. So he will PRODUCE LB3! So I got hired to direct. I think it's because I kinda look like Sean. We're both incredibly handsome, beefy, bushy haired surfer types. Sean's just more talented. But at least I'm bloated.

No word on when the next film will arrive in theatres!

Dont't forget to also check out: Legally Blonde 2: Red, White, & Blonde