It will only be used if they offer transparent delivery, just like Opus in YouTube.
Not a single person knows what Opus is, but they all know what YouTube is.
For normal people, MP3/AAC/FLAC will remain standard FOREVER...
Its not just the size, you also need to take encoding speed and battery life in consideration.
Why are people still using MP3 compared to Opus?
Why are people still using H.264 compared to H.265?
Why are people still using JPEG compared to WebP?
With the advance of 5G, I don't really see a need for these very low bitrate fornats...