Re: Oh dear.
An engineer that did that would be very clearly out of their depth for the task.
For one thing, an extra byte isn't enough, so you'd have to go through the entire process again in a few decades' time. For another, you can't just tack an extra byte on. You still have to go and add a new record type to DNS (like v6 did), and add a new socket type (like v6 did) and a new socket API to handle the new types (like v6 did), and update RAs/DHCP (like v6 did), and update all the other standards that hard-coded v4 (like v6 did). Everybody would need to update their software to handle the new sockets and DNS types (like they do for v6) and configure their networks to use it (like they do for v6).
Your suggestion omits all of those necessary steps, and if you add them in then you basically end up with something that looks the same as v6 does -- except it's too small and would itself need to be replaced.