So, around the mid 90's what should have been done is IETF "We need everyone coding a TCP/IP stack to update their #DEFINE LEN_IP_ADDR from 32 to 64 bits and the same for LEN_IP_MASK. Front PAD any v4 TCP addresses with 4 x 0 when translating between V4 and V6 addresses. If you can't reach the next hop send the DESTINATION NET NOT AVAILABLE code in the usual manner".
This will be IP protocol V6.
New IP stacks could have been rolled out in as much time as it took the BSD crowd to code it, and others to implement the code in their OS/device. Weeks or at most months. IPv4 only devices would be museum pieces by now. A wistful Reg article on the passing of IPv4, commented on by a few greybeards, while a PFY mutters OK Boomer would all that marks its passing. "Imagine that, IP protocol with only 2 to the 32 addresses!"
(Errors and omissions are the fault of Surface horrible gummy keyboard)