Why would you care what address your PC is using ? If your ISP gives you an other IPv6 assignment your router should just advertise that and your PC will use it. You wouldn't even notice. If your router doesn't do that is has a bad IPv6 implementation. The protocol itself is perfectly fine for that. That is one of the big stumbling blocks for IPv6: bad implementations in networking equipment.

Causing a conflict in your LAN with address is a problem of IPv4 and the tiny address space it has. It forces you to keep a tight administration and use a bolt on address space management technology like DHCP. IPv6 does not have that problem and you'll have a service less to run.

Indeed, it's not trivial. Many parties will have to do something. I hope they'll get more motivated as the price for IPv4 addresses rises even further. When CGNAT solutions get starved of socket space and adding extra IPv4 addresses gets prohibitively expensive maybe IPv4 will get so slow and unreliable people will give up on it.

The graph of IPv4 address space pricing gives some hope: https://postimg.cc/QKKx847B