Considering Universal clearly doesn’t want to release specifics until next year, I think this teaser image was just right.
If you read the Facebook comments on that Attractions Tickets post, most are folks saying they didn’t know it was a coaster, so I think the teaser image did exactly what it needed to. It’s telling people to expect a new Harry Potter Coaster next year, because the general public doesn’t know that yet like we do. (The only official announcement so far was buried in a blog post about another ride closing that was geared mostly to locals.)
And I think it’s important to focus on the coaster element first with this one, so people know what to expect. If you just go out and show a picture of Fluffy and say something magical is coming, you’re going to have a lot of folks that don’t/can’t ride coasters upset when it opens. They’re putting the emphasis on the right thing for now if you ask me.
Now, next piece of info or images has to really explain the scale, because some of the comments are wondering if it’s just like Flight of the Hippogriff.