Do you really think digital voice will bring immunity to interference? I don't. When I turn on the office computer my APRS station stops receiving packets. And that's only 300 baud data. You'll still need power to overcome the QRN, and a noisy FM signal may still be intelligible where a digital one won't. I also think you overestimate the ability of newly licensed, cash poor hams to adapt cheap old radios to work in the digital regime. The amount of technical knowledge required to obtain a ham radio license these days is negligible.