Exactly this misconception comes up (often multiple times) every time there’s a discussion about IPv6 on HN.
No, it’s not possible without running into the exact same problems that we had with IPv6 (which actually has various compatibility mechanisms, to the point where now some mobile networks are IPv6 only but still work to let people access IPv4).
The problem with your proposal is the same issue we have now - something that only talks the old protocol can’t possibly talk to something in the new protocol (without the same kind of hacks we use with IPv6 like NAT64/464XLAT), since IP addresses in headers are fixed sized. Which also means that any router in the middle can’t possibly route packets to networks with the expanded addresses. So we have the exact same issue - everything needs to be upgraded to deal with your new scheme, but unless that all happens on the one same day, you need to be able to deal with the old addresses. So you need dual stack, just like with IPv6 until everything is transitioned.
So basically all you’d have with this kind of proposal is exactly the same problems, but it would be more confusing why older devices can’t talk to the newer devices since the addresses would look very similar!
No, it’s not possible without running into the exact same problems that we had with IPv6 (which actually has various compatibility mechanisms, to the point where now some mobile networks are IPv6 only but still work to let people access IPv4).
The problem with your proposal is the same issue we have now - something that only talks the old protocol can’t possibly talk to something in the new protocol (without the same kind of hacks we use with IPv6 like NAT64/464XLAT), since IP addresses in headers are fixed sized. Which also means that any router in the middle can’t possibly route packets to networks with the expanded addresses. So we have the exact same issue - everything needs to be upgraded to deal with your new scheme, but unless that all happens on the one same day, you need to be able to deal with the old addresses. So you need dual stack, just like with IPv6 until everything is transitioned.
So basically all you’d have with this kind of proposal is exactly the same problems, but it would be more confusing why older devices can’t talk to the newer devices since the addresses would look very similar!