According to The Hollywood Reporter, Legendary have hired Shang-Chi and early G'14 writer Dave Callaham to pen the next installment of the Monsterverse!
https://www.hollywoodreporter.com/movies/movie-news/godzilla-x-kong-follow-dave-callaham-1235895879/
After the fantastic box office takings of GxK it was pretty obvious we'd be getting more, so I'm glad they're confirming it early rather than beating around the bush and acting like we didn't all know that was going to be the case. Granted I didn't think Shang-Chi was anything amazing, but then it's not like the writing has ever really been the strong suit of these movies anyway.
I'm sure they'll get Adam Wingard back again once he's finished with his recently-announced A24 film this year too, so I think for better or worse we can expect another entry that's very much in the same vein as these last two. Either way, I'm just happy we've officially got more (movie) Godzilla on the horizon once again!