Everyone wants new content I get that, but its always everytime whenever there is a new update people always automatically assume its Brewster. I get it people want him back, but I haven't seen anyone even talk about like the possibility of brand new characters being introduced. Now I know that sounds Controversial but hear me out. What if instead of Brewster returning it could be someone related to Brewster?
Think about Daisy Mae, she replaced Joan who was the original NPC that was selling Turnips. She learned how to sell turnips because Joan taught her how to do it. To get back to the point it can be a new NPC that is related to Brewster that will setup the Cafe and they learned a lot from Brewster to know how to serve coffee. He/She will be the one to visit your island and you can buy food items from them and they will visit more often. Once you buy from them, they will be able to give you a Cafe Plot kit to place on your island to set it up.
I know what I'm saying may sound shocking and probably outlandish, but think about it. If Nintendo wants Animal Crossing New Horizons to be fresh and they are treating it as a reboot then it will probably make sense to add in more new NPCs that we haven't seen before that play the same role as the Predecessors, but they do it in their own way (Like CJ and Flick). This may or may not happen it will depend on Nintendo if they want to bring back the old NPCs or have them replace with some new ones that will mention them when you first meet them.