Just recently Sprint purchased rights to Zact software and in effect shut down Zact MVNO from operating using their priority software which allows a customer to choose small chunks of data, voice, text (Build your own plan). VM is now using this model.
This will be very interesting to watch.
See if they make the free service less useful.
I could also see a gsm carrier buy Freedompop. Didnt Feircewireless do an article on FP that they were interested in partnering with a GSM carrier as well? Again, it's mostly customer base one would be buying in this transacation. Websites and software can always be modified to handle the carrier chosen.