STM32 Nucleo development board supports Arduino

Basically, the new Nucleo boards support only connectivity to Arduino shields, but my question is - would Arduino ever support any STM boards in their IDE???

I'm intriqued by the STM32F401 M4 MCUs where you could get similar/better performance as the SAM3X in a package as small as 3 x 3 mm. ( a bit smaller than this ---> ? ) at $2.72 each for qty 3K.