Tipping satellite radio

What exactly will it take for satellite radio to tip over and become common use for the masses?  Certainly having Sirius and XM installed as OEM equipment in vehicles helps, but what more can be done?

According to this post on Engadget, Sirius Satellite Radio has struck a deal with Walmart to distribute their product.  Certainly there are no other retailers that could give Sirius the kind of boost in sales that Walmart can.

I was recently in a remote area of Washington where radio signals were few and far between, and the stations that did come in consisted of Hispanic-format broadcasting and country, neither of which would be my first choice in what to listen to.  Some of the people that I was with had satellite radios in their homes and cars; it was a necessity if you were looking for radio programming as opposed to CDs or an iPod.  What was the biggest store in the area?  Walmart, of course.  Everyone in this area of Washington shopped at Walmart, and there are lots of areas of the country where there is a similar situation to the one I described in Washington.

Lots of the people that I talked to in this area of Washington had a fried or friends with satellite radio, but had not yet purchased because it simply was not convenient; they had to drive 3 hours to Seattle to find a good deal.  With Walmart carrying the product, I would guess that a lot of people in this area of Washington would quickly snap up a satellite unit.

Personally, I'm very happy with normal radio and my iPod.  To be honest, I listen to my iPod 90% of the time.  However, if I did not live in a metropolitan area and wanted to listen to the radio the other 10% of the time, I'd probably pay $10 per month for satellite service.