Compatibility of bloks will be chaotic, we will see the same problems (eg: some bloks work only with some other bloks, software will be tuned to particular bloks). More brands get involved, more chaos
Each and every blok will have to be replaced at the same pace as the entire device, if not faster, given the rate of progress and changing standards. Manufacturing screens, batteries, storage to variant specifications might actually be more wasteful... We may end up with more tons of waste bloks than phones
Not sure what the role of any mobile company in the current state of things would be in such a blok process. Their job is basically to get the qualcomm, broadcom, Texas instruments, atmel/synaptics, corning/asahi, arm variant, toshiba/samsung components to work together at particular prices.
This thing will be bulky, each component has a shell to start with. Dont think the teardowns of any device will reveal an advantage in changing the space alloted to storage vs battery for cloud / non cloud based usage as shown in vid.
What is fun is you can switch over 3.5 mm jacks and charging port to any side as per convinience.