Every time there's a discussion about IPv6, a suggestion like that appears, without fail. Paraphrasing the classic spamsolutions.txt, "Your idea will not work. Here is why it won't work."

"Requires immediate total cooperation from everybody at once": every single system which wanted to talk to an AWS host would have to implement that IPv4 extension.

"Many server administrators cannot afford to lose business or alienate potential clients": for anyone with a non-upgraded system, the server would be unreachable.

Specifically, your plan fails to account for:

- Lack of centrally controlling authority for networking

- Huge existing software investment in IPv4

- Popularity of NAT and other middleboxes

- Users who don't update their operating system ever

and the following philosophical objections may also apply:

- Ideas similar to yours are easy to come up with, yet none have ever been shown practical

- It will work for a while and then we'll get stuck with it

- It's an ugly hack

"Sorry dude, but I don't think it would work."

(I apologize for choosing your comment for this, but this idea of applying the spamsolutions.txt format to the inevitable "extended IPv4" proposals has been in my head for a long time. Someone with more networking experience should be able to present an even more complete list of "extended IPv4 objections".)