Is losing Taylor going to kill Spotify? No. But Taylor's label seem to be singling out Spotify, while her music remains on Pandora, iTunes, and iRadio and other streaming outlets. So it's not about the money, or streaming, but specifically Spotify.
I was at a conference where a streaming service was complaining about not having access to all catalogues. He was asked by a music industry rep why they need to have every song on their service. The point was that brick & mortar record stores never had complete catalogues in stock. Why do streaming services feel they need complete catalogues. To be honest, I don't have an answer for that. But I'm just conveying the view of the music industry.