This isn't how I've understood the change. My understanding is that developers will need to have their ID verified before they are authorised to allow their app to be sideloaded. So long as they have done that, why would the user need to have a google account to sideload the app? Wouldn't the whole thing be transparent to the end-user (for those vendors who pass the ID verification) and the only thing they'd notice is that they can no longer install the apps from vendors who haven't passed?