Personally, I think Coco will go in Pixar Pier. The land desperately needs it more, and Hollywoodland is prime real estate for either more Avengers.
This is certainly the prevailing expectation of where Coco is going. But I think it would be a mistake. It locks this "land" into being a potpourri based on one of Disney's studio brands that normie consumers just don't feel that strongly about.
For decades I made consumer products with the overall Pixar brand and individual Pixar movies, as well as with other CGI studios such as DreamWorks, Illumination, Blue Sky, etc. -- and I can say, mass audiences don't know the difference. They generally can't tell you which studio made which movie, except for a few exceptions. And they really don't care. It's inside baseball.
It's like knowing whether Warner Bros., Universal, Sony, Paramount or 20th Century Fox made the Mission: Impossible movies... people don't know and don't care. What they care about is the movie/franchise. (I know the animation studios have more of a "house style" than the live-action productions from a given studio, but it's not distinctive enough across movies to differentiate from other CGI movies for normal people.)
All that is to say, a land based broadly on Pixar is not connecting viscerally with guests like a different movie/franchise theme could. Especially when you mix in the non sequitur pier amusement park aspect (what does that have to do with Pixar?). The Pixar umbrella theme is a placeholder at best. Yes, the land needs more, but what I think it needs is a single relatable theme (e.g., Toy Story, or Frozen) so that moms, dads, and kids can have a clearly envisionable and discussable thing to get excited about.