For many years I have tried to keep track of how the traditional telecoms has fared against the emerging VoIP application world (what they sometimes derogatorily call “OTT”). I have had two hypotheses for several years now:

Traditional telecoms over the PSTN is past “peak” and will continue to decline
Real time communications (RTC) in general has been on the decline but is poised to make a comeback thanks to better implementations and technologies like WebRTC

Read more about the article here:
https://bloggeek.me/webrtc-save-telephony/