Part of the move involves the company selling off up to 2,400 or so retail venues to Standard General (its largest shareholder).
The new model, if finalized and approved, means that RadioShack will exclusively sell Sprint mobile devices and services (including Boost and Virgin Mobile). It also means that Sprint branding and products will occupy approximately a third of the retail space per location.
Basically, RadioShack stores are becoming Sprint stores. Sprint has about 1,100 retail venues at the moment; the RadioShack deal would more than double these locations.