your right, looks like IHeartRadio's deal to stream the Cumulus station may had expired and both sites agreed to part ways.
for now on, any Cumulus station that streamed on IHeartRadio will be streamed only on their station's respected site or their station's app. example, if you want to listen to 820 AM WBAP out of Dallas, you have to listen on WBAP.com or the WBAP app for IOS and Android.
this is where you go to find a Cumulus station to access their website to listen to the stream on their sites:
http://www.cumulus.com/stations/
so go there, find your favorite Cumulus owned station and listen to your favorite Cumulus station via their website.
their webstream is built into the actual site and is HTML5 friendly, meaning no flash needed.
it could be possible they maybe working out a deal to bring their streams on another streaming service like TuneIn, Radio.com (currently owned by CBS Radio but will be owned by Entercom once the Entercom/CBS Radio merger is finalized), or they could launch a unholy alliance with Spotify or launch their own in house web streaming site/app to compete with IHeartRadio, TuneIn or Radio.com. heck i wouldn't be surprise if Cumulus buys out TuneIn to make them their version of their rival companies sites/apps.