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.
You seem pretty obsessed with the topic.
It's just one more flavor of youtube as far as I'm concerned.
I wouldn't say obsessed, just interested. I'm mostly a clip viewer anyways and a lot of why I'm asking this question is because of how much Eastern media is being consumed by the West and the fact that idol culture is a massive part of corporate V-Tubing especially. With Hololive's first 3 English generations about to do a concert at Kings' Theatre and Yagoo's very clear push to try and make the industry mainstream in the West, it came to mind.