You're entitled, in this context, to explain what could have been done during IPng (which began in 1992). Just not to go back and fix IPv4 so that it makes your job easier. Otherwise "obviously the addresses should have been wider from the outset" is the tedious answer to everything (except maybe "would IPv4 have still taken off, with such baggage?"). Any time estimates should be real world, so for example, having begun planning in 1992 you will be too late to make an impact on the project Microsoft are jokingly calling "Windows 93" and which will eventually ship as Windows 95.
Surprisingly little has changed in IP, except in cases where two peers can identify that the other implements some newer feature. Most of what gets done in the stacks is optimisation, taking advantage of features that exist in the specification already. And sometimes even that fails - just because the specification says you can do something, does not mean it always actually works in the real world. Life is full of disappointments.
Yes, there will be a mess. That is not a new observation. We have no useful prior experience to judge exactly how big the mess will be. Some of the things we've been doing to try to give ourselves more time will, as with NAT, contribute to the mess.
FWIW Options 1 and 3 are the only ones that look reasonably likely. Option 3 is really bad, but only in the same way that widespread private ownership of motor vehicles was really bad. It didn't bring about the end of civilisation or anything, and it made our culture what it is, for better or worse.
Option 2 basically won't happen NOW (even in the unlikely event you can come up with a better alternative in our "What if?" scenario) because it would be too late to the party. Achieving even IPv6's tiny penetration will take an alternative decades.
Option 4 won't happen because people like captioned images of kittens. An expensive, inefficient network that continues to deliver cat pictures is still enough to keep the lights on at the ISPs. I'm being flippant, but millions of people are now used to having this service and paying for it. Address exhaustion doesn't make that demand go away. Of course "as we know it" could be construed to include Option 3 in some ways. A network without end-to-end is not the Internet we thought we knew and loved.