Yes, they allow BYOD but on plans in line (or more) than postpaid.
I'd be OK with a BYOD plan on prepaid if it mirrored postpaid pricing within reason. A 60 a month (for example) BYOD plan, unlimited everything, no throttle or maybe a 5GB cap.
It would keep ARPU respectable, and they would save money by not having to pay roaming fees, device subsidies, and using offshore CS.
They can ill afford more voice roaming, they pay a lot in postpaid roaming fees and something NV and a bit of 800Mhz love is supposed to minimize.
The CDMA side of Sprint (both postpaid and prepaid) have been gaining subscribers.
What they need to be is profitable and that's been elusive since 2005. Once NV is completed, redundant cell sites decommissioned, roaming fees are reduced, as well as the expense of running two networks is put to rest, I think it happens. They can make money with it's current number of subscribers, it's the past bone head decisions that still haunt them.
T-Mobile still makes some money (as of Q3/2011) with less subscribers and for arguments sake, lets say a comparably sized network footprint. T-Mobile is grasping for any customer and will become a huge prepaid carrier (and it's just my opinion) since it continues to loose postpaid customers in droves.
This new Straight Talk and Net10 BYOD offering is going to be interesting. Maybe it will pressure Sprint's prepaid divisions to change. I'm not convinced it will until it's truly tested. Many have complained of having data turned off for what was considered excessive use or voice for talking too much.