A little note. Just because something can be enjoyed by everyone does not make it "not for kids". The Pokemon games are for kids, and that's a fact.
For everything else, you have to understand that this is a Japanese show. Even if kids in other countries don't like Pokemon as much as teenagers or young adults, doesn't mean they will change their target age range for you. If it's doing well enough in Japan, their target audience, there is no reason to change it.
Pokemon was CRAZY big a while ago, and even if it doesn't reach that super high level again, doesn't mean it's not doing well. It's doing more way more than well and will continue as what it's mean to be, a game/anime/manga series for children, that can also be enjoyed by adults.