Will there ever be a point when things like this don’t happen in movies or on TV? Is that in the foreseeable future? Or is it just an impossible thing? Will there always be some cartoon rat on some cartoon network who’s obviously Mexican or black or Asian or whatever?
Ultimately, it comes down to writing and writers (and producers in an editorial role). Young writers are often taught to “write what you know”, so if they don’t know any better, they’ll continue to write stuff like this. Producers have to be better as well (but they probably skew older and whiter and thus less likely to see the problems).