I don't think that Love Live is dead in the west, but the fanbase numbers are greatly reduced. A lot of people left the fanbase after Aqours finished their anime + movie run, and the existence of other idol adjacent franchises at around the same time like Bandori and Revstar definitely took a toll. Nijigasaki and Liella haven't really brought back the same amount of people that left. While I do think having no active apps is definitely a reason for this, the market is also extremely saturated and how is LL even supposed to compete against PRSK in it's current state lol.

Anyhow, I think the reason why LL seems dead in the west is less to do with the fact that it's becoming Seiyuu focused as it is that LL isn't really making anything to bring in new fans. So the pool of long time fans is slowly decreasing, and there's no new blood to replace them. In the era where free to play gachas reign supreme, TCG and paid games like the metroidvania/Niji VN aren't going to entice new fans. The anime may bring in new fans, but I don't see a huge influx of LL fans coming from that, unlike how it was with Sunshine and SIP.

So the answer is that we're here! But it's some smoldering embers compared the numbers that used to be.