The thing hurting Ting the most right now is devices. Devices come out frequently, and Ting is shackled to a lethargic supply chain. If Ting could just register MEIDs and IMEIs itself instead of having registration tied to buying a phone from Sprint, then Ting could get out of the device business (as they have stated they want to), and users could purchase the unlocked phones they want and provide the MEID/IMEI to Ting to begin service.
I know there's more to it than that (like turning on various features), lots of moving parts, red tape, etc. But, other mobile companies can do it, so it must be possible (even if not with Sprint). To me, this should be Ting's top priority, because when it's solved, the sky is the limit for Ting.