Maybe it won't be the 'brain', but will it be the voice of the IOT, and through the IOT to many kinds of goods and services? I would still bet on Google or others sculpting the brain, but Amazon is leading the pack on voice services and existing infrastructure.
" ... Amazon has sold “millions” of its Echo Bluetooth speakers with Alexa inside. Now that hundreds more Alexa-enabled devices are coming to market, the benefits to Amazon will grow, and quickly.
Amazon smartly made Alexa an easy to work with, flexible program, much like Apple did with the iPhone to spur app development. It is essentially creating an operating system for the home, one that will connect the myriad of smart devices in the Internet of Things to each other and to Amazon. ... "