My suspicion is that they're not going to get rid of that functionality -- it continues to be a differentiator between them and Spotify. And, assuming that's right, they don't have any particular pressure to get rid of the standalone iTunes Match service. I know there's the argument that they might get rid of the $25/yr service in order to force people onto the $99/yr service. But it seems quite likely to me that Apple figures anyone still paying for iTunes Match but not Apple Music just doesn't want Apple Music, which makes the consideration in Apple's accounting department not "$99 > $25" but "$25 > $0".
https://www.imore.com/apple-music-vs-itunes-match-whats-diff...
My suspicion is that they're not going to get rid of that functionality -- it continues to be a differentiator between them and Spotify. And, assuming that's right, they don't have any particular pressure to get rid of the standalone iTunes Match service. I know there's the argument that they might get rid of the $25/yr service in order to force people onto the $99/yr service. But it seems quite likely to me that Apple figures anyone still paying for iTunes Match but not Apple Music just doesn't want Apple Music, which makes the consideration in Apple's accounting department not "$99 > $25" but "$25 > $0".