There have been many developments that clear some problems due to which usable android could not be ported, like the memory requirements and closed source video drivers.
But now, Broadcom has released the source code for a VideoCore Chip, and the latest iteration of android(KitKat) is optimised to run on low power systems, like the Raspberry pi, with the minimum memory requirement being reduce to 512MB.
So, my question is, if working open source drivers are ported to the Pi, wil it be possible to achieve fast and usable android on the Pi?