What would happen if Apple launched its own free Podcasting hosting service atop already existing free iCloud accounts?

There is real precedence for this in this history of free hosting accounts (could happen on Google Drive or Microsoft OneDrive too). With Spotify's acquisition of Anchor (also a free host), it makes sense competitively soon. 

It's a question worth examining - but in the end, it really changes nothing for anyone who takes their Podcast seriously.