Yea the way I look at it, T’Challa is basically a mainstay Avenger, he’ll always be appearing in some kind of team book where he can interact with other heroes, whether it be the Ultimates, the Avengers proper, or some other secondary team. So while I’m not opposed to team ups and T’Challa working with other heroes in his main book, he’ll already be doing that in a specific team setting.
I 100% agree he’s more than just a Wakandan character and given the tendency some writers have to focus too much on Wakanda I’m all for T’Challa spending more time abroad, meeting foreign heroes, and leading non-Wakandans. But I don’t think that should override his own mythos or the need to develop his own supporting cast and rogues gallery. So I’d like a nice balance, which is certainly achievable as writers like Priest and Hudson showed.