Its unclear whether App.net intends to charge all of its users $50 per year forever. It does seem clear that in order to remain ad-free, the service will need to keep charging folks to access the service, and thats obviously a hugely limiting factor.

That may not be a bad thing. You can listen to the radio for free, but you have to pay for albums. Thats why you can listen to an album without commercial interruptions, but not your favorite local FM station. SiriusXM offers numerous ad-free satellite radio stations, and pulls it off byyou guessed itcharging an annual fee. And why terrestrial radio has an order of magnitude more listeners than satelliter radio does.

And yet both coexist. Both forms of radios have many contented listeners. But Im willing to wager that SiriusXM subscribers listen more, on average, and enjoy what theyre hearing more, too.

So I dont expect that the worlds most followed Twitter usersyour Kardashians, Gagas, Pinks, and the likewill make the move from Twitter anytime soon, or ever. Nor, I suspect, will most of their fans.

But App.net doesnt need millions upon millions of users or celebrities to be successful; it just needs interesting people I care about following, and a healthy third-party ecosystem to support it.