I don't think this is going to be just a small update to include Brewster considering they've let us known two weeks in advance and it's going to last 20 minutes. If it was only Brewster and that's it, they would have included it in the general Direct.
There was a very cool thing datamined a while ago, a 100% map expansion to the south. It would be cool to have a second island, or another island a la New Leaf, this time without loading times. I hope this is really a thing.
It's very exciting because we all love the game and know there's potential to make it even cooler. I love it very much already, and I would say it's my favourite Switch game with BOTW, but there's tons of untapped potential. And then there's all the content that they could bring back which would be amazing to have. I miss the rococo set I had in my house in New Leaf, and the beautiful japanese objects that are still missing today.