By 'mainstream', I mean that Vtubers like in Japan would be on the morning talk shows, be featured in advertisements on TV, have shows about V-Tubers on TV (there is a light novel with an anime adaptation called VTuber Legend: How I Went Viral After Forgetting to Turn Off My Stream), collaborations with V-Tubers and sports teams are a common occurrence, and while we have had some of these things in the West, it's not as pervasive as it is in Japan.
In my opinion with Western media being continually ass, it's only a matter of time.
The point was whether or not it would be successful in the west. Have you not seen western media, it's half the point of this forum. Black, ugly woman, or severed penis is mainstream Western media. Hot white women with nice looking anime chick's would not be allowed.