I dont think that blockchain-music-technology will ever replace spotify, deezer and apple music. mainly because all the mainstream is there. I believe that in the independent-music sector a lot is going to change but a lot of "listeners" enjoy the fact that most of their favourite music is available on spotify. Those users collected artists, album and saved playlists for a couple of years now which makes them even more dependent to this platform. Also, even when you consider yourself "not mainstream", the line between independent music and mainstream is very blurry. some ppl might start out with madonna and end up listening to chinese grind core (of course that always happens if you listen too much madonna ;-))
So keeping your music on spotify is a good idea so new fans can discover it and if you are able to catch some of them with a newsletter subscription you can send them to new blockchain-platforms.