So, that opens the door to a free competitor that does not charge. The wheel turns once more...
And then all the businesses on Fritter notice that no one is reading their freets (frites?), and either give up or go back to Twitter and pay the twax.
Doesn't really sound like that promising a business plan, to me.
But, there's still the problem of Twitter. There are so many Twitter based apps out there, that spread their brand which means there's about 6 gazillion sites other than blogs, and now news sources like CNN, that actually promote the use of Twitter. Twitter is big.
In other words, maybe the best way for someone to take down twitter is to create a compelling reason to not use facebook's status feature, and instead use the next new thing.