That truly would not concern me. I appreciate what Mixon has provided here, but he is showing signs of the usual short RB shelf life, as we all kind of expected, and it'd be a good time for fresh legs anyway. If I felt that the RB position is hard to replace I might be less nonchalant about it all, but I tend to believe that it's the single most disposable position among the starting 22.
Now I'll grant that I wasn't thinking about it at all until the "warrant for an arrest" appeared on my screen. But I don't consider Mixon an essential piece.