Re: Won't happen in my lifetime
NAT does not make firewall rules simpler, it makes them more complex - now you have two sets of addresses to worry about and logs to correlate between them, and this often results in errors and/or security problems cropping up.
Firewalls already ship in a deny by default state, you have to add allow rules.
Addressing doesn't scale... It might work for a tiny network, but on a network of any scale ipv6 is much better unless you have totally screwed up your addressing plan.
Consider for instance zoom:
100+ ipv4 ranges, or a single large ipv6 range.
or consider an ISP such as Sky:
a single large IPv6 address block which covers all their infrastructure and customers, vs a bunch of disparate ipv4 blocks all over the shop.
With IPv6 you have flexibility to develop a proper logical addressing plan for your organisation, microsoft wrote a good document about this...
You have a single address prefix for the company - eg 2001:db8::/32
Then you split down according to location, to vlan etc, so your office vlan might be 2001:db8:100:22::/64... If you use a logical addressing plan you can already calculate the first half of the address based on where the system is located.
The second half can be statically assigned, can be made memorable, can be auto generated - the choice is yours.
IPv6 brings many advantages, but people are resistant to change, dont want to learn anything new, and many of the advantages are only realised once everyone else is onboard too. Tech companies like microsoft and facebook have migrated to ipv6-only networks and pushed backwards compatibility legacy ipv4 to the border.
A lot of it is inertia, if you are willing to learn ipv6 properly then you realise that it will save you a lot of hassle associated with ipv4. If you don't learn then you don't know any better, and are used to all the painful kludgy workarounds.
From an end user perspective there are advantages too, but there is no marketing so users don't demand it. If the providers which already had IPv6 started promoting it to users they would pick up a lot of customers from those that don't until they were forced to follow along too. Users will ask for newer/better technology if they are aware it exists, even if they don't understand why it's better.