No surprise. Gone are the days when people bought home stereos or even home theaters. That's really as much a statement on the change in the consumer electronics industry as it is for radio, since they're related. ...
But yes, people can't listen to the radio if they don't own one, and the fact is that local talent isn't a good enough motivation to get people to seek out radio receivers somewhere (a bigger challenge since consumer electronics stores have almost disappeared.) If home receivers are going away, then radio companies better have a streaming plan.
You bring up the point that electronics are changing and improving. That has sculpted the market as much as content. Those are ultimately the two defining factors of any media.
In the 70s, you'd have to buy a large set up of receiver and speakers in order to get an excellent audio experience from electronics. Today, thanks to microarchitecture and other advances, you can get a fairly nice audio experience from small speakers and a computer, or a rather small am/fm receiver.
In the 70s, a large audio rig to give you a fair audio experience would set you back about $1000 in today's money. To get the same audio experience today, you need maybe $200-or-less (if you own a computer for audio content). And the modern stuff takes up less space and has more functions!!
But the reason so many electronics are failing to sell, and why the electronics market is changing, is ultimately that the CONTENT is not engaging people. Who would spend $5000 for an amazing TV-stereo-theater rig when there is nothing worth watching? Why buy any radio if all radio is boring? Despite electronics getting cheaper and higher quality per price, the content is dismissed by most people. (Yes, there is still a profitable audience in all media, but it is a much smaller audience these days than prior to online/streaming).
The laptop/desktop/phone/tablet is now a superior product because it lets you listen to audio, write mails, contact people, take photos, view photos, write papers, watch video, do work. So it is a premium quality device, and people will flock to content on there because it is fresh and connects people to a wider range of entertainment.
However, these computer-devices have lousier audio. No fear! Audio mastering and music has generally adapted people to lower-quality audio over the last few decades via compression and. "loudness wars" and distortion of instruments and sounds. So the fidelity of FM radio isn't valued by the audiences.
So now most people merely gravitate to the content and not the quality. But price plays a large factor: why would people pay when they can free-milk a cow? That is why terrestrial radio is still so strong! It would have vanished if other media was completely free. Many people will NEVER subscribe to satellite radio due to free radio being so accessible. There are many who will subscribe, because they have the disposable cash, but not as many as get free radio.
On the content side, FM radio is now massively conglomerated and homogenized. Most radio is McRadio, and even worse for radio sales--these McRadio stations are streamed online!! So why buy a radio? Younger people (cash strapped) merely listen on their all-in-one smart phone. Who needs an actual radio??
And an even darker side of content, the gateway to radio via internet streaming offers overly repetitive content, corporate-stale content, ridiculous sounding voices saying ever-decreasing levels of humor, intellectual content, worthy news, or engaging entertainment. It is a slurry of regurgitated culture and immature jokes or phony personalities.
Thus the results of. the Edison research. Thus the current state of radio.
What is the future? Online and ultra-local. The market will divide more and more into the future, as the iDevice generation/s get older. Everything will go online, but the unique mom-pop local-news FM content will have a strong appeal to the local audiences. If it isn't ultra-local, it will be online. Anything that is super-successful in the ultra-local market will most likely get pulled up to the McRadio online and pushed via streaming devices.
People will continue to buy radios, but they will be small, inexpensive, and multi-functional like many modern radios that cost $50, get AM/FM, connect to the smart phones, have alarms, etc.