While the first bit will still cost $20-, the average price per bit will come down dramatically for heavy users.
I still want to see the app. I want to be able to use with my iPad, MacBook, PC, and iPod Touches. If I cannot do all the things that I can do with my Vz MiFi and save money, I will not switch.
I use the MiFi in fits and starts, often with months going by when I do not use it at all and others in which I blow through the max. Therefore, there is opportunity to save money. Also, while I never go anywhere without my iPhone, the MiFi is another device easily forgotten.