iTunes Radio was the holdout, offering ad-supported streams to users, because the service had been in place since 2013. However, iTunes Radio no longer offers a "free", ad-supported version of the service, and if you want to still have access to those streams, you will have to pay the Apple Music subscription fee. Apple Music's Beats 1 will now be the only "premier free broadcast" offered, because that service is not on-demand.
Of course, if you like having on-demand radio mixes, this doesn't mean you need to start paying for Apple Music. There are still plenty of options to get you what you want. Spotify and Pandora still offer on-demand radio mixes based on a song or artist that you're feeling at the moment. And, Google Play Music offers free on-demand radio not only based on a song or artist, but based on your mood or what you're doing.