I think you're getting a little too excited. Coulter wasn't even a top 10 Brewers prospect by BA or BP before the season, and they don't exactly have a great system. He's going to need to keep up this hot start for a lot longer to make Top 100 lists.
Two days ago Jason Parks had this to say about him: "Production is never a bad thing, but I see a really strong mistake hitter right now, and I'm not sold the bat will carry. I also don't see a catcher long-term, but that can take time and he can improve enough to make it work."