I bought myself an STM32F401RE Nucleo and Tiny BLE from Seeed, just to have some real mbed enabled platforms as a reference. I hadn't looked much into mbed before and was unaware that you actually need 2 MCUs for mbed enabled platforms, one to act as a debugger, UART-USB bridge and fake USB storage, using ARMs CMSIS-DAP platform and the other one as the actual user programmable MCU.
This is only a slight problem though, as two EMW3165 can likely be used for this purpose, one as CMSIS-DAP and the other for programming via mbed.
I've not actually started working on a mbed port yet, but just wanted to make ppl aware that it seems to be a possibility and that you'd need 2 MCUs for it. CMSIS-DAP is available from the ARM website, but you need to have an ARM developer account, though the free ones work fine.