I'm looking for someone to either shoot me down or to indicate whether this is plausible.
Could it be possible to write apps to run on a Cortex-M4 micro? Storing the ELF files on an SD card, reading them into RAM as and when necessary then executing at the entry point. Could these ELF files link to a common library which the main application on the Cortex-M4 uses (almost like a common API for the platform) as well as any ELF files on the SD card?
It all seems pretty feasible but I'm probably missing something huge.