>>30750183There's like 5% tops, and that's a seriously high estimation, of their being ANY overlap between those 2 fanbases.
The baseball hype is fantastic, but a lot of those people don't even watch Nijisanji at large, and extremely less likely to watch idol stuff.
You'd get a few people here and there sticking around for sure. "Oh that's that vtuber thing? This looks pretty cool, I might check them out", but for the most part those people just go back to their regularly scheduled lives.
Viewer retention for popular interests is very low in general beyond those events, even when they usually intermingle with the people hosting it.
A lot of people are content in staying in "their own field" and not straying too far from it.
It's why you see a lot of people saying "subscribe for more" in videos, it literally works, loads of people consciously don't decide to sub unless it is pushed in their face quite blatantly. (the dumb subscribe animations don't work well at all, it needs to be a fully audible, content distracting sequence)
